Hi Craig,
I think it depends on the State you are moving to.
We had considered getting an international licence in the UK before we moved since we had heard that we could drive on it for 6 months before taking a test - I think it's actually 3 months regardless. In South Australia they no longer do a driving test if you are from the UK. We took our licences into the council office, filled in a form and had Australian driving licences. We did ours within a week since we were told (incorrectly!) that we needed an Australian licence to buy a car. We've since found out that was wrong. You only get a basic licence so if you need HGV or something like that then you need to set a test again. Also if you wear glasses but have never been told that you to wear them then you can get your licence quicker by saying that you've never been told to wear them and have your photo taken without your glasses. If you are in a hurry for your licence this is what we were told to do (I wear glasses because of astigmatism but have been told I have to wear them for driving). If you have to wear glasses for driving you need to take an eye test.
See
Apply for a Driver's Licence
for more info.
Regards,
Karen