G.B.
I sent the kids to Head Start at 3. They did fine. I think that if you look at a school that is set up as a pre-school and not a child care you will see a difference too.
If you are happy at the child care center then I think you should leave him there. He has plenty of time before he starts kindergarten to do a whole year of pre-k that is offered free through the local public school system.