We have this discussion lots at school. Muppitty is right that a child has to turn 5 july 31st in NSW to start kindy and must start school by the age of 6.

I am a kindy teacher and in my opinion she is too young. You could still ask the school for an interview but another year at preschool wont hurt. You can still get her ready for school by teaching her the sounds that all the letters in the alphabet make, get her to do some writing (doesnt matter if its not correct- jsut as long as she is experimenting with writing) and mosst importantly get her looking at books and expose her to them as much as you can.