I know a few people have said that they do rolling acceptance based on when you submitted your application but I don't think that is correct. I submitted my application in December and I got accepted, and I have seen few posts similar to my experience.
I think they do rolling acceptance in the sense that they send out offers to their first choices and then based on the number of offer acceptances, they send out another batch of offers. They probably rank the applications for each stream, and then send out the offers based on this. Also, I am sure that they are still reviewing applications for certain streams, such as health promotion, which is why some of you may have not heard from them yet.
These are just my thoughts!