Pacificjet,
12 months should be plenty of time. I applied in February a couple of years ago, had the YOU session in March, spec. testing April, assessment day in late May, file got to PSA mid-July, position on next available course (25 Sep - 09 Oct from memory), was told of an offer from a certain FLTLT at PSA in late October and officially received the offer in November.
Of course if your friendly DFR is not on top of their game, you'll have to poke and prod them to get the ball rolling and get yourself in for your various tests and interviews in a timely manner.
Check out google for free online IQ tests for basic stuff that you'll find in the YOU session and the RNZAF website for the more aircraft specific stuff in the spec. testing.
Enormous amount of advice on the whole process in this thread. Have a read!