The time the NZ flight arrives is the tail end of the morning rush. I'd allow a minimum of 2 hours, perhaps 2 1/2 hours if onward ticket is cheapest/least flexible type. If australian/nz passport then 2 hours is sufficient unless you travelling at the start or end of school holidays.
Originally Posted by number_6
Unfortunately QF is requiring that both flights must be on QF to use the free bus
Is this a recent change? I have many times arrived on other airline and departing on QF (for int->dom and vv for dom->int) and never been turned away.