Nat, every state is different which is stupid in this day and age where people move interstate. I think NT is based on SA so they have an intake at the start of each term up until term3 and you have to have turned 5 before you start. This was called Transition in NT, we called them the trannies which used to make me laugh. In NSW a child can start in the year they are 5 or will turn 5 by 31st July that year. the problem with this is that there is a huge trend to "holding them back" largely due to the perception of some people that their child will be better and smarter if they start late. Some children ARE too young socially or emotionally to start young, particularly boys born in June or July but in some areas of Sydney particularly where I work we get kids held back who are born in Feb. or March which means you have classes with 18 months age gap in them. At our school Riley would be really unusual if I sent him the year he turns 5 which really pi$$es me off as he may be OK to end but do i want him to be labelled as young? It depends on the area you live in, when I started teaching at Mt Druitt, most of my kindy class didn't turn 5 until June or July.
Sorry I'll get off my high horse now, its one of my pet peeves. Basically you need to look at the individual child and take the advice of preschool teachers or the school. Everyone has very different opinions on this and can get jst as passionate about the opposite view LOL. I was lucky with the girls cause there was no decision they just went.