As many have suggested, if you have the option, take the first base offered as direct entry to other than MEL/SYD are rare. From the last list (May), time (mths) to basing (most junior positions)
MEL/SYD- direct entry.
NTL - 4
ADL - 7
CNS - 9
AVV - 10
OOL - 13
BNE - 15
PER - 24
Command - 7y8m
of course these can vary greatly as fleets and demand changes.