Not knowing what your career goals are makes it difficult for me to recommend schools.
1st or 2nd round are absolutely the best times to apply. If you wait until 3rd round, most of the seats will be taken. Do not apply in the third round. 1st and 2nd are essentially equivalent.
Being Canadian has no implication on acceptance (positive or negative). There are a number of Canadians accepted to HBS and othe rUS schools every year.
I didn't see a bunch of leadership experiences in what you mentioned.. The supervisory role is good, but be aware of your leadership style and how you're having an overall positive impact on the organization.
Also, with a low GPA, you'll most likely need a better than average GMAT score.