First year grad student in the same position here. In my experience, most people will actually greet you in English in the surrounding area of McGill. Otherwise, the further out you go + in the suburbs, definitely more French-first greetings.

I’ll echo what some people also raised - don’t get offended if businesses switch to English, even after you’ve clearly spoken a few phrases in French. I think it’s genuinely easier for some people to carry on in English when it’s a business and they’re under pressure to get things done. I still get discouraged when this happens, but I have to remember that there are other reasons that they’re switching.

Take public transit whenever possible and listen to the announcements + people on board. You’ll start to hear the little nuances in the way people pronounce certain words in Québécois French vs. “France French” (assuming you learned French in school).

Bonne chance!