How do I stop thinking about how many hours there are left on the weekend?

quit your job and chill for 2 years and discover a new type of depression

Slipping into a nice K-hole.

Choose something else to worry about.
For example: I worry about the ever-decreasing time limit on life: Death
Problem solved, now I have a new problem.
🙃

I don't have an answer for you, but I can absolutely relate. Some people say something like "find a job you love, and you'll never work a day in your life." But for me, it doesn't work that way. I like my job, have awesome coworkers, and always look forward to the next week. But obviously I'd still rather be doing things I enjoy more. You know, playing that latest video game, finally finishing the Lego set I bought three months ago, hanging out with friends, etc. Two days out of seven just isn't enough time to do all that, which leads to anxiety about optimizing the little time I have.
One thing that has helped me somewhat (and I know I'm very privileged to be able to do this) is taking every other Friday off. A two-day weekend versus a three-day weekend makes a huge difference for me. I'm actually considering switching to having every Friday off. But then ofc, there might be the dilemma of having the time to do the things I enjoy but not enough money for them :(
- Yes, fully agreed! Yeah at the moment I need to save money, but working less, like 80% seems like a great thing. If one works 80% then one can rotate the days so every other week is a 4-day weekend. Luckily I have no co-dependants at least

Try and find a job you don't hate.
I lucked into a book called 'Discover What You Are Best At.'
Turns out, when you aren't miserable about going to work, a lot of your other problems vanish.
- Thanks for the book rec but as I mentioned in other comments, I know that there won't be a job which I'll enjoy doing 8 hours a day for the rest of my life. I even enjoy my current job sometimes, but I still rather be without it if it was possible. And I've also tried different sectors already... Either way, I'll check out the book.
  
  I was like you; I thought that I hated work and was going to spend my life doing stuff I hated.
  When I did the tests in the book I was shocked to find I had talents I'd never realized.
  I had never even considered the job I ended up liking.
  There are all kinds of jobs out there that you've never heard of.
- this is really a big part of it. folks who have "pre-monday" dread are dreading something and I feel like we all owe it to ourselves to find a way to work that we don't dread.
  Ikigai, the Japanese philosophy, sums up a good way to try to think about this.
  https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcQShgM4AHjckIHaFUzk8efCvggw6p5MvDNTMQ&s=
  OP if you're reading this, I feel you, I've been thinking about beginnings/endings/time remaining since I was a little kid and its a fuckin curse, frankly.
  As a few people have mentioned, mindfullness is a good thing to learn a bit about and to try to "do" basically every day if you can remember.
  You dont need to sit listening to a person who's doing the "spiritually tuned in reassuring relaxing voice" that mindfulness people make the mistake of doing.
  If you stop, put your feet firmly on the ground and feel the floor under your feet (rock your weight up to your toes and back to your heels and really feel the solid quality of the ground for just a sec) thats called 'grounding' typically, then take one slow (5 secs or so in and another 5 out) diaphagramatic breath (breathe down and into your belly, not the chest, your belly button should go out instead of your breastbone) and thats it. you'll now remember whatever youre looking at the next day instead of just going through the motions of your weekend free time.
  things end and death is coming for all of us, but not now, and thats worth checking in to
  
  I don't really hate my job to be honest. It's just that, no matter what I'd do for pay, it will never be anything I really want to do. I'd rather spend my spare time pursuing whatever studies, hobbies, exercise or random leisure I really want to do. Capitalizing on your interests doesn't lead to anything good, at least for me. People always say, "try to find your dream job!" but for some people, there will never be. Because capitalism and 40 hour work weeks are unnatural in itself. But yes, mindfulness and meditation is key, still.
- I play a lot of idle games in my free time. I really enjoy getting home from work, setting up my machine and watching it work.
  So, I went and got a factory job where I go in, set up my machine and watch it work for 12 hours. I'm really good at my job, too, because I don't hate it

I have the opposite problem. I sit down Friday evening, and before I know it, it's Sunday night.
- I swear I last remember sitting down and it was 2019. Now by bones are half dust.
  
  I'm not entirely convinced that it ISN'T still 2019, and I just haven't woken up from the longest, strangest dream I've ever had.
  
  Tell me. I recently dated this blonde girl and suddenly I'm divorced, burnt out and middle aged. Ok, I still got two cool adult kids.

I would say meditation could be helpful. Being present in the moment instead of looking forward prevents that creeping dread. Likewise planning things you want to do like hanging out with friends, going to shows/movies, and group activities will probably have you focused on those on those instead of starting your week
- For sure. I have a steady meditative practice, but still, it takes a long time to change one's mind and it's easy to forget...
- And, by extension, mindfulness. Which is more or less what you describe I guess.

That makes two of us.
I even keep thinking about not going to bed for some time just to extend the weekend time.

Quit your job.
Though this solution will cause other problems, you probably won't care about how many hours are left in the weekend anymore.

The irony of pointing this out when there is literally one less hour of the weekend this weekend...
- Not in my country :)
- c/USdefaultism

Anti-anxiety medication

I used to look forward to weekends and would often postpone personal projects to the weekends where I would have the time to do them.
It's a lie. I don't have time in the weekends. There's always something else in the way, because everyone else also want to connect in weekends. It only causes frustration from not being able to do whatever I actually want.
It's also bullshit that I have to postpone private stuff for weekends. I want to live my life 7 out of 7 days. Not 2 and then work 5. I'm not happy with giving 70% of my life away, and hoping to catch up in the remaining 30%.
It might seem somewhat egoistic, but if you want time for yourself, you will have to prioritize time for yourself. That includes giving lower priority and more often saying no to work, friends and family. If you try to please everyone, then your time will be consumed by everyone. You have to put yourself first and align other people's expectations.
However, it's not really egoistic. It's better to be fully present when you're doing stuff with others, than to sit at their place wishing you were home. That includes work.
Also, I'm now focusing on carving out time in weekdays for the things I want to do. No more overtime work, no more procrastenation and relaxing just to prepare for the next day. Sure, I will work the agreed hours to make money, but I am going to take ownership of the rest of the day. That's somewhat easier in the summer where I have more energy and the weather is better. In the winter I am almost hibernating but then I also lower my expectations for what I can do.
So in short, it's necessary to plan your time and it's necessary to align expectations from others but also your own.

Sounds like your subconscious is not satisfied with the activities you’re up to on the weekend. Maybe you could do something g that’s more meaningful and you’ll be more engaged and therefore less distracted by the clock, which is a fairly boring thing.
Try waking up early, as if you have work or school, and starting the day with exercise and food. It’s a great way to make the day seem longer.
- This is what works for me. If I’m productive in things I want to do, instead of have to do, I’m fulfilled and okay with going to sleep on Sunday night and not thinking about it. If I feel like I waste the weekend then I have an issue mentally with going to work. Mind, if I’m exhausted and want to spend the weekend watching YouTube or whatever then I’m okay with it. It all depends on mindset.

Monday

A little mental trickery you can use is to move to calculating how many hours have passed when you start thinking how many are left.
The brain is lazy, and creating extra effort will gradually make it avoid the original thought in the first place. It will also make you think about what you have managed to do, and the relax you have taken, instead of projecting into the things that are to come, that, since they are not already done, seem more tiresome.
This advice comes with 0 guarantee of success from a completely unreliable source. Take it with a grain of salt. In my case it works pretty well.

I work 7 days a week and I don't have this problem.
(Jokes, I do, but I like both my week job and my weekend job)

Stare at a clock for 2 minutes. Genuinely. I find it helps reset my perception of time

When I had that, I solved it by changing jobs. I loved my job, but everyone was stupid about work live balance and stress management. I realized after I changed that I really should have changed jobs sooner.
- Can't say I have large issues with my job tbh. It's fine. I sometimes even enjoy it. But yeah, I'd rather not have a job at all if the world was made like that.
  
  That's good!
  Another thing I do is to make plans for Sunday night. Then when I look ahead to the end of the weekend, I have my Sunday night plans to look forward to, and not just work on Monday ahead.

I basically have a schedule of things I want to get done planned ahead of the weekend. I keep myself occupied and don't worry about the time left before Monday. I do the things I planned and I'm so focused on what I'm doing I don't worry about anything else.