Hi! Normally, if your child will not be able to complete a school year in the Phils and you move here in AU, he/she needs to repeat the grade level when you enrol him/her in a school here.
What you can do is as early as now, even if you're still in the Phils, you check in the Internet for possible primary school you want to enrol your child This is what I did before we migrate here and I was able to enrolled my son if before coming here. I sent email to the schools' principal and asked for the school enrolment requirements. Though some of the principals will not reply, but most of them will and hopefully you'll find someone you like.
You can start looking at this site - http://bettereducation.com.au/SchoolRanking.aspx 🙂
Good luck on your search! 🙂