Technically anything after 12am would be "morning" because it's a new day.
However, generally early morning would sometime between 3 and 5. If you wake up at 3am, it's early morning. If you go to sleep at 3am, it's late at night.
Anything after 5am is just morning (unless you're being goofy and calling everything night because you didn't sleep).
(These aren't specific rules, just how it is in my region - other people might be totally different)