I dont know about any other states, but in NSW you don't need any temporary rego. You are legally allowed to drive your car without any plates for registration purposes (e.g. driving to an AUVIS (blue slip), driving to get CTP insurance, driving to the RTA)
I rang the RTA about this on Thursday and i actually got pulled over by the cops on Friday when i was going to get my CTP insurance and Rego!
I told the cops what the RTA told me and showed him my Rego application, import approval, blue slip, proof of purchase, etc. (whatever documents needed for rego) and he let me go...