In WA we have Kindy first which is non compulsary, but is part of the primary school system, onsite in the primary schools and all part of the same school, it is currently 2 full days or 4 half days (very rare though these days) and is curently being phased in to 2 1/2 days a week (or 5 days a fortnight) and child start when they are 4 (turning 4 before 30th June the year they commence, otherwise they start the following year).

Next is Pre-primary, also part of the primary school system- this is also non-compulsary (but there is a push to make it compulsary) and it is 5 full days per week. Children start pre- primary the year they turn 5 ( 5 before 30th June the year they start, or they have to wait to the following year).

Then we head into the primary school school years 1-7. Currently though they are working on moving year 7's into high schools- the catholic and private system have started already, with the public schools set to follow soon.

At the moment, Kindy and Pre-primary are not compulsary, however if you think your child is too young for kindy the year they are supposed to go, you can not send them the next year to Kindy, they have to go straight to pre-primary. Same goes for missing pre- primary, if a child misses it year they were supposed to go, they have to go straight into year 1 the next year.