Baby won't fall asleep alone

Serina
My son is four months old (3 months adjusted) and he won't fall asleep unless he's on my chest. At night I'm able to move him to his crib without a problem, but during the day, I can't put him down for a nap. If I move him off of me during the day, he wakes up. When did your little ones start falling asleep on their own or least not wake up when being put down?