Our DD8 was "early-entranced" to K with a birthday 9 days past the cutoff. It was good for that year, but she was still academically ahead in almost everything and so we followed that up with subject acceleration in 2nd grade and then a full grade skip into 4th. So, the early entrance was the right way to go for us but wasn't enough.
With our DS6, we knew he was ready for K last year (and really the year before that) but we didn't think they'd consider early entrance for a boy with a b-date almost 3 months after the cutoff. So, we kept him in the preschool that he enjoyed three mornings a week. But, as the fall approached we were more and more certain that he should not be in K. So we talked to the school, he was tested, and then subsequently skipped K. It was a great move for him. He is still years ahead academically but is in all other ways a 1st grader.
I would see if the principal of the public school would consider letting your DS sit in on a K class for an hour or two now to see how it goes. Obviously, he'd be with kids a year older than him, but it would be a good way to observe how easily he separates from you, how well he interacts with the other children, whether he will get involved in the activities in the room, etc. If he fits in well, it might convince the principal that your DS would be fine in K next year, especially if the K teacher said nice things.
Also, I would ask the principal in what ways could he be placed in the right learning situation if he were to wait to go to K year after next. Would he be talking enrichment, subject acceleration, a skip to 1st? I'd try to nail it down a bit.
Many of us here have been in the same situation, so I hope we can help!
