Yes, you can be based in Australia straight away, but not on the 777 or the -400, at least not in the near future. It will be on the Airbus.
I would act fast, as the bases fill up quickly at the moment.
But think about that, there will probably NEVER be a command slot available on the australien bases.
Now with the retirement age of 65 commands in HKG will be around the 12 to 15 years mark.
And please, think twice to leave a major European Airline for CX.