We are in NJ for the summer and they have 10/1 cut-off and parents are holding back kids with summer birthdays because they think K is like grade 1 and their kids are not ready. I cannot imagine holding DD back, even if ND. In NYS you cannot for public school. You start late, you go to grade 1 and catch up, expecting you went to preschool when you were suppose to go to K.
This may be true for NYC but not New York State. People do hold their children back and they go to K a year later. As a matter of fact I sincerely doubt that if you keep your child home for K (outside of NYC), the school will be willing to put the child to the 1st grade without a fight.
Good luck with riding the bike in Manhattan
