It changes constantly. I'm watching a flight for March 10, and the availability was 3 in CW yesterday, and today it is 6.
A few weeks ago, a family member was booked in CW (MFU) outbound/ WT+ return. I checked on MFU availability for the return literally every day for weeks. One seat finally opened up two days before departure.
I would keep looking every day. I know that Australia tends to be a different animal than other routes, and have no experience with it, so hopefully others have more input.