I don't think it really matters which way you do it as the qualification is the same all over the world, but you're right in thinking that it might help you if you do it in the country. The tutors will know of vacancies, either at their school, or in others around the city. Full time CELTAs, I've been told, are very intensive and good fun because you are studying with like minded people, full time, and so build friendships and contacts.
Cost is also a factor though. Spending one month not working and paying rent, if you'll be renting in Canada, can add a considerable amount to your outgoings.
IH Vancover is £1350 Full time and IH London is £1635 Part-time. You could of course opt for cheaper courses in Europe and save some money whilst experiencing living in another country for a month. It works out cheaper.
Depends I think on your circumstances. I would chose the latter option, but if you have a partner who doesn't teach, or can't take one month off work...