I booked a trip to montreal and then realized my passport was expired. I went in without an appointment. Get there early. Wait in line. I got there maaaaaybe 30 mins before they opened and already a long line. But they get you in and will triage. Ie: if you have a flight tomorrow they will do yours first, before someone who is flying in 3 days. I got mine next day. Just show up early….bring a coffee, snacks, earbuds & charger and plan to camp out there for the day. But it did work for me.