What visa are you on? If you have
PR then you will be covered by medicare as soon as you arrive. You do have to wait about 10 days before you can apply though but if you need a doc before that then you just go to one and pay and claim it back once you've registered.
We havent sorted private insurance yet but will have to after July otherwise we'll have to pay a medicare levy surcharge as hubby earns more than the limit (dont know of hand what it is) but as he's only been working half the year this year he wont have gone over the threshold.
Sam x