Ho Chi Minh City is 15 hours ahead of Portland
Best overlap: 5:00 PM to 6:00 PM in Portland is 8:00 AM to 9:00 AM in Ho Chi Minh City.
If you set up a recurring sync, 5:00 PM to 6:00 PM in Portland (8:00 AM to 9:00 AM in Ho Chi Minh City) is the natural home for it. With overlap this short — around 1 hour — a recurring slot at 5:00 PM in Portland (8:00 AM in Ho Chi Minh City) is worth its weight in gold. This window straddles two dates — Portland's today is Ho Chi Minh City's the next day. These times hold for most of the year, but Portland's daylight saving (which Ho Chi Minh City doesn't use) shifts them by an hour twice annually.