Ho Chi Minh City is 12 hours ahead of Ottawa
There is no standard 8-to-6 overlap. Someone joins early or late.
When Ottawa starts work, Ho Chi Minh City is already winding down or offline — the 12-hour gap leaves no shared window. Default to async and only schedule live time when it genuinely needs a conversation — then make it count. For part of the year the maths changes: Ottawa observes daylight saving, Ho Chi Minh City does not, shifting the overlap by an hour.