In WA children born after July 1st start school the following year. My DD was born in the latter half of the year and while it hasn't done her any harm at all (as her teachers are challenging her academically) she could easily have started the year before.
My son on the other hand... He also was born in the latter half of the year. HE was not ready at all. In fact he has started Kindergarten this year 2 1/2 days. and is coping really well academically and socially but still not adjusting to the separation anxiety, even this far into the year! I couldn't imagine him being at school last year. He could barely speak then! He would not have coped at all.
I do worry about my DD turning 18 right before Tertiary entrance examinations! No you can not drink, or go clubbing UNTIL you finish highschool, even though you are legally an adult who can vote... I am sure we will manage. Just.