Address change is MANDATORY. You MUST advise IRCC of the new address when you move. You can do this once you are able to access ECAS.
The AOR letter that you get clearly mentions the following :
The reason why this change is important is because when your application goes to "In Process", the file is transferred to visa office that is responsible for your address. If you update this information ASAP, when your application goes to IP, it will be sent to the correct office in the first go. If you move before you get IP but you decide to update the address later - IRCC will take its own sweet time to move your file from the office that your application is currently in to the new office in Ontario.