I'm really against the 15 days (CA). Since just before Christmas, I've sent a number of packages to branget the day he paid me for them, sent them international priority (6-10 day delivery) and not have them even leave the states until 15 days even though I did pay for the priority.
In fact I had one instance around the beginning of January where I sent Boozad (in England) and Branget (in Canada) packages on the same day, and Boozad got his just at two weeks and Branget received his after 3 1/2 weeks.
I always send out the delivery confirmation number, so that my recipients know its been posted and can check online to see that I dropped it off, but 15 days to Canada (unless you just happen to live very close to one of the processing centers) is sometimes out of the seller's hands.