We are doing this with my son. Where we lived prior he made the cut off by 4 days but then they changed the date to Sept. 1st as well. He was 4 when he went to private K. We moved to SC where, if in PS, he would be finishing 2nd. We decided we would go with that. So we are really doing 3rd. for 2 years. I also didn't want a 17 year old graduate or him to be the youngest in his "grade". (For co-op and church they use the grade level.)