Date: 2018-02-23 14:30
In order to forward to international addresses, you need to fill out a paper form at a US post office. US post office employees may tell you (as they did me) that you can do this all online, but they are INCORRECT. The online form only works for changes of address within the US, which is obviously not helpful. For international relocations you need to get the paper form in person, and if you fail to do this before leaving for Canada you'll have to write a letter to your formerly-local US postmaster and hope he or she is helpful.
If you have any way to open a Canadian bank account in advance of your move it's going to make your life a lot easier. When you open a new bank account, the first check deposit you make into it may not actually be accessible to you for a period of time (may be up to a month depending on the bank) so if you can get this out of the way before you actually need to use the bank account it will be more convenient. Consider depositing cash instead of a check if you can, as this will be available right away. Also note that it will take 7 weeks to get any checks for a new account, and depending on your city, you may be asked for post-dated checks to pay your rent, so this can cause some issues with renting an apartment. And, the sooner you open a bank account in Canada, the sooner you can start building up a credit rating which will make it easier to get a credit card right away when you arrive. If you don't have a bank account until you arrive, you probably won't be able to apply for a credit card until you've paid a few bills/received a few paychecks, in other words, a month or more. If you'll be in that situation, be aware you'll need to keep using your US credit card for a month or more and ensure you have funds to cover it still in the US.
You'll need to get a new mobile phone number in Canada, which means switching out your sim card from the old phone. Remember that nowadays your old phone number will be tied to all sorts of online accounts, such as your bank account, and you'll need to log into all of them and update your phone number before the old one stops working, otherwise if you forget your password or need phone verification for some other reason, you won't be able to do this. Also, there is a big difference in mobile phone plans so it's worth doing some research on the best deal depending on where you live. If you'll be in a big city, some of the smaller, newer companies like Freedom mobile offer excellent deals with unlimited texting to US and Canadian numbers which may be worth checking out as well as the "big name" providers.