12 week old sleep schedule

How do you get your baby on a schedule? My son turned 12 weeks old yesterday and he sleeps so much still. He’s been asleep since roughly 12-12:30 last night and its now 1pm. He woke up once at 8am and again at 10am to eat. He still stays awake for about 1-2 hours and then sleeps for 1-2 hours. I try to play with him but his mood instantly switches when he gets tired. He could be smiling and having fun and then the next second he’s crying cus he’s tired. What do I do? Do I even do anything or let him adjust to being awake himself?