Ho Chi Minh City is 11 hours ahead of Montreal
There is no standard 8-to-6 overlap. Someone joins early or late.
Montreal and Ho Chi Minh City are 11 hours apart, and that gap is wide enough that their normal 9-to-5 workdays never quite touch. If you meet regularly, fix one off-hours slot and rotate it between Montreal and Ho Chi Minh City so the burden doesn't fall on one team. Keep an eye on the calendar — Montreal observes daylight saving and Ho Chi Minh City doesn't, which nudges this window by an hour twice a year.