I started potty training my son (3 years 4 months) 2 days ago. He finally has had success peeing in the potty but I noticed he holds it in the morning for way too long and when he finally sits on potty he screams and cries if the pee leaks out and he tries to hold it longer. He says he doesn't want it to come out. Anyone else experience something similar?

I do a reward system which he likes. If he sitsnon potty after he gets an m&m. If he makes on potty he gets a small prize.