Schedule naps

Hi!

How did you start getting your baby on a schedule?

Max is 4.5 months old, and is sleeping well through the night. He takes random naps all throughout the day. Sometimes 10 minutes, sometimes an hour and a half. Random times too. He sleeps a total of 10 hours or so per day. Now gets over tired and very cranky. I feel like a schedule will get him to sleep more and be happier.

How do I start? Do I keep him up until 9 am? Then try to put him down? Do I let him cat nap and then try to put him down again at 9?