Adelaide is 2.5 hours ahead of Ho Chi Minh City
Best overlap: 8:00 AM to 4:00 PM in Ho Chi Minh City is 10:30 AM to 6:30 PM in Adelaide.
The overlap falls at 8:00 AM to 4:00 PM in Ho Chi Minh City, or 10:30 AM to 6:30 PM if you're in Adelaide. The 2.5-hour gap barely gets in the way — you've got 8 hours of overlap, so pick whatever time fits the agenda. The window above shifts seasonally: Adelaide keeps daylight saving while Ho Chi Minh City ignores it.