Guessing ours average 3-4 weeks. I thought a google would spit it out clearly, but no .. Go to Essential steps .. the closest i've found ..
The Act requires at least 33 days between the issue of the writ (the writ is an instruction to the Australian Electoral Commission (AEC) to hold an election) and polling day (although it can be as long as 68 days after Parliament is dissolved). As the election date is generally not known until the Prime Minister calls an election, the election campaign generally happens in the period between the issue of the writs and polling day. Election day must be a Saturday, so it is possible to determine the last possible day on which an election must be called to be held on a certain day. https://www.aec.gov.au/learn/election-timetable.htm