The Waterloo students I've worked with have been absolutely amazing and have tons of programming experience. They do co-ops year-round. If you're running a startup, I'd recommend putting a post on Jobmine, which is their online job matching tool: http://uwaterloo.ca/jobmine/

The next deadline to post a co-op is January 15, for students working in summer 2014.

(You can technically post now for the "continuous cycle" of Jan-Apr co-ops, but I think most students are already matched so you'll get fewer results.)