You are eligible to apply for a postal vote if you are unable to get to a polling place on election day. The Australian Electoral Commission encourages you to apply as soon as you know you are eligible. https://www.aec.gov.au/election/pva.htm
The AEC cannot send your voting pack until the ballot papers have been printed. The earliest the AEC can send out your pack is 26 April 2022. If you do not apply as soon as possible, you may have to choose an alternative way to vote.
If you are a registered general postal voter and your postal address has changed or you have been affected by events such as natural disasters, you can update your postal address online. Submitting your ballot papers
Ballot papers must be completed and witnessed on or before election day. You are encouraged you to do this as soon as possible after receiving your vote. Follow the instructions on the inside of the postal vote certificate. Once you have completed your postal vote, return it inside the white return envelope provided. The address to use to return your postal vote will be printed on the materials you received.
You have only 13 days after the election for your ballot papers to be received by the AEC. For Further information visit: https://www.aec.gov.au/election/pva.htm