Ho Chi Minh City is 11 hours ahead of Atlanta
There is no standard 8-to-6 overlap. Someone joins early or late.
Given Ho Chi Minh City is 11 hours ahead of Atlanta, the realistic answer is that there's no convenient shared slot during normal business hours. Catch the edges of the day: the last hour for Ho Chi Minh City or the first hour for Atlanta is usually the least painful option. Because only Atlanta changes its clocks, the overlap above isn't fixed; expect a one-hour shift when Atlanta enters or leaves daylight saving.