@chinky If you have a PR visa then you can use your LTO license for up to 6 months only after that you have to apply for an Australian license. For cases like me na temporary work visa lang I can use my LTO license for the whole duration of my stay here in Australia which is 4 years. Pero I may have to renew it before that kasi ang LTO license is valid for 3 years lang kasi. See excerpt below from Victoria State overseas license guidelines for your reference:
"The requirement to change your overseas driver licence to a Victorian driver licence depends on whether your stay in Victoria is temporary or permanent.
If you are in Victoria on a temporary visa, you can drive on your overseas driver licence for as long as it is current providing it is in English or accompanied by an English translation or International Driving Permit. There is no requirement to get a Victorian driver licence.
If you have entered Victoria on a permanent visa issued under the Migration Act 1958, you may drive on your overseas driver licence for:
<b>six months from the date you first entered Australia if the permanent visa was issued before you entered Australia; or,
six months from the date when the permanent visa was issued to you if the permanent visa was issued to you whilst in Australia.
If you want to continue driving in Victoria after this time you must change your overseas licence to a Victorian driver licence</b>. "
See more details at : http://www.vicroads.vic.gov.au/Home/Licences/NewToVictoria/OverseasDriversLicences.htm
hope it helps.