Am i right in thinking you are allowed 3 attempts at both the POC and AIB? If you used up all 3 attempts at either POC or AIB, then joined the corps as a recruit, would you be unable to go for a corps commission?
no that isnt the case. I have a friend in recruit training at the moment and he says a lot of guys who were not successful in officer selection have started recruit training.
I would take Ninjas advice, Ive waited until my last year at uni to go through selection - no point doing it before you are ready.
Also to your point about corps commission after recruit training. If you do well in training then you can apply for corps commission almost striaght away - given time that is - otherwise you can wait until you get a few of your stripes before doing it.