You can be pretty sure that you will get whatever Regiment you want. Which Battalion, I have no clue. Most likely, where they need you, you will go ;D
Up until week 12 of BMQ I was PPCLI, than I asked my Sgt. on a march back to Farnham about switching to RCR and he told me to put a memo in monday morning. By tuesday I was RCR.
Furthermore, day 1 in Meaford I was told by another Sgt. that if any of us wanted to switch to PPCLI that we should put in a memo. He told us, reason being is that the CF would rather have a happier soldier than a pissed of soldier who diffinatly wouldn't re-sign his contract after 3 years.