I didn't know it varied from state to state. I guess I never thought about it.

My DS turns 5 on 15th Jan. We're in NSW.
I think when I started kindy I was 5 turning 6 cause our birthday was in the middle of the year.

It's hard with birthdays at the start of the year, cause they're either going to be younger then others or older, depending on which way you go. (if that makes sense)