Being a January bub, I turned 15 at the start of year 10 so I was one of the youngest in my class. I really think that you should make every effort to hold her back if you feel that strongly about it, but on the other hand there have been plenty of kids who at the start of a year seem quite young emotionally, but by the end of the year they are fine and have 'caught up' to their peers, and going to Kindy helps with all that kind of thing as well. So maybe that is one avenue to explore too, send her and if at the time when you have to decide to send her to school you can make a decision then if she is ready or not. It may even be easier to do it that way, because then you have the backing of her kindy teacher and her input on whether she thinks your DD is emotionally ready for school.