I never went through CMR (that's what we call RMC St Jean) so I'm more familiar with the path that RMC folks take; however, I have a general idea of how things work at CMR.
What has been happening for the past couple of years is that after enrolling, you are placed on LWOP (Leave Without Pay - once you swear in, you're a member of the Reg Force, full time employed by the CF, but you're not working yet, so you can't get paid). Your LWOP goes until the first day of your INDOC course. RMC and Civ U candidates do this at CFLRS (colloquially known as the Mega - the place where all Reg Force basic training happens), and I don't know if CMR candidates do it at CMR or CFLRS. I think it's been CMR in recent years.
After INDOC, RMC cadets go to RMC for FYOP, which is worse by far. CMR cadets do OP, which, from what I hear, isn't as bad as FYOP. You would be best served by speaking to someone from CMR (I think SeR is from there) and getting specific info regarding INDOC/OP and how that all happens, because I think CMR kind of does their own thing, different from RMC.
Either way, what it will practically consist of is about a month of training before classes start. You'll learn how to wear the uniform, maintain a kit/inspection standard, probably sew your name into a million pieces of clothing, do PT, fitness test, drill, lectures/classroom teaching on military ranks, rules/regs, procedures, handling of hazardous materials/workplace safety, and on and on until your eyes hurt from powerpoint.
BOTC/IAP are irrelevant acronyms for you; once you finish your first year at CMR, you'll go to CFLRS to do BMOQ (Basic Military Officer Qualification - colloquially referred to as bee-mock). Look up the series 'Basic Up' (I believe it's on youtube) for a bit of a glimpse at what to expect during BMOQ.
Make sure you're in good shape when you show up- fitness level is one of the biggest weaknesses with a lot of first year OCdt's, so make sure you're fit to lead, because one day you're going to lead soldiers.