You can receive the as soon as you have a subscription to lucky magazine (which I did before I even knew about the discounts), and I don't see anything that says it wouldn't work in Canada.
The magazine is fun and a subscription is cheap. If you ask for their best price,you can get the first year for $12.
You can subscribe over the phone and they will give you a lucky numer which allows you to get the discount right away. They send out the gift cards 4 times a year--April, July, October and January.