My daughter started going to the "school" starting the beginning of this year. She is two. I say school in quotes because it is a Montessori school, but they accept children for daycare too. They do teach her, and she has actually learned more then I thought she would at that age.
If he is 4, he may go to VPK. Florida will actually pay for children to go to VPK. If not, you can write off the daycare expenses.