I tell the parents to register the child as normal come January and that gives them till summer to decide to send them or not. Over the year look at some of the developmental charts and chart the child's progress to see if there are specific areas that are really weak which is masking other areas. There may be ways to work on those things to get the child ready. On the other hand some with Dec birthdays - especially boys do benefit from waiting the year to start school. Some parents choose to put the child into a kindercare type program at a centre instead which gives them similar benefits to JK but a smaller ratio with built ins like a full naptime.