You will get a place in your local school whenever you arrive in Australia, but of course the school needs to look at your lease document which must bear the name of a parent. Out of zone enolment will be very difficult if the school is very popular.
In NSW the cutoff date is 31/7, ie when a child is turning 6 before 31/7 in 2015, the child can enrol into Yr 1 in 2015.
Your child was born in May 2006, so s/he will be turning 9 in 2015. The child may be enrolled in Yr 4, but s/he will be among the youngest in the year. You may talk to the school for holding back a year, ie enrolling in Yr 3 if you consider it more appropriate for your child eg socially.