You can apply for a .au domain name right now. After auDA (who are in charge of domain name registrations) checks whether the web address is available, you’ll either get your new .au straight away or will need to participate in priority allocation process.
If someone else has dibs on the domain you want, then you also have the option of waiting until 21 September 2022, when the priority allocation period ends, and then all .au domains will be freely available.
