Hey, I'm a running mom myself
The 5-7 weeks may be an overestimate, but to be sure I'd have your friend ship it to you from the US. You can change the account the Kindle is registered to when you receive it. All ebooks are downloaded from amazon.com, but it will realize that your home country is Canada from your account data. All charges are in US$ (but no tax!). You will notice that as a Canadian, not all ebooks will be available to you and some will have different prices that if your country was the USA.