The point is that you MUST submit your application while you are in Canada. Do not send you application from Boston. You can drive to Montreal and submit from their for sure but again try to make your mailing address in Canada and the home address in the US. Good luckunfortunately I am teaching a class this semester, and I can only go back to Canada for a prolonged period in May 2018. So it's a choice between sending the application from Boston, or driving to Montreal and sending it from there.
I have the feeling that it doesn't matter either way.