All airlines require the issuing airline (AS in OP's case) to do any rebooking except for irrops, so there is no advantage or difference on day of flight changes or at the airport. In practice it is next to impossible to make this kind of change and easiest done by phoning AS directly. Nothing unique about QF in this process (except the extremely high demand for J seats due to flight length and demographic of travellers on this route, making awards highly sought after).