The last proven activity dates back more than 4500 years, to Mount Gambier. But Australia is not virgin volcanoes so far: there are about 150, extinct or dormant.
The majority of volcanic events appear between two terrestrial patches, with zones of friction. Australia being in the middle of a plate, it is relatively spared.
With an estimated activity frequency of 10,000 years, it is likely that the activity will resume in a few thousand years.