For all those wondering: St-Jean has been filling up first for a large variety of reasons: here are just a few.
1) Language Fluency: If you marked yourself as bilingual, there's a good chance you got considered for RMC St-Jean first.
2) Major: St-Jean is the international studies school. That being said, the first year of many programs (and in fact, almost all the programs) can be taught with the resources present at St-Jean. As your university career continues, all those not pursuing a degree in international studies will go to RMC Kingston for the rest of their degree.
3) Trade/Occupation Offer Demand: As you know, you can (and usually do) apply to not one but three possible occupations. As a rule, admissions tends to fill high-demand occupations first (see the higher number of combat, construction, and aerospace engineer offers this early in the season). That, coupled with the desire to fill St-Jean first before Kingston, means that those occupations also tend to have been selected for St-Jean before offers are extended for Kingston (like me!).
4) Random chance: In some cases, it really is random! And that's okay. Remember: if you truly want to go to Kingston, and only have an offer for St-Jean, you can a) sit tight in St-Jean for a year or b) if you'd prefer another occupation anyway, simply turn down your current offer and hold out for your other occupations as the weeks go by.
Note: Did you get in for an occupation that you don't want as much as another, or still haven't heard anything? (Looking at you, Air Crew) Don't panic! This process takes time and your recruiting centers have a lot of paperwork to fill. Sit tight: within the next six weeks, offers will have fully rolled in. You will be considered for all your possible occupations equally, and will be given an offer based on the needs of the forces. Don't like an offer? You can turn it down with no risk to your chances for the other occupations.
Hope this helps, and congratulations to all those who have gotten in so far.
See you at BMOQ!