@whitecarnations my son went to pre-school for two years – he was four at the end of his last year. The program we were in had a kindergarten option and since he would be 5 by December 1st I was able to put him in it. He went to that year of kindergarten but because his birthday was so late and because he is a boy (and boys mature more slowly than girls), I put him in our neighborhood school for a second year of kindergarten. I knew parents who didn’t have that option so they put their kid in an extra year of pre-school.
FYI, holding him back was one of the best decisions I ever made. He is in 7th grade now and in the state where we live the cut off for kindergarten is September 1st, so had I started him when he was four he would have been the youngest kid in his class.