Dallas is 13 hours behind Hong Kong

There is no standard 8-to-6 overlap. Someone joins early or late.

The 13-hour offset between Hong Kong and Dallas means there's no point hunting for a 9-to-5 overlap — there isn't one. Expect compromise: someone in Hong Kong or Dallas will need to take the call outside the usual 9-to-5, so share that load. Finally, Dallas observes daylight saving and Hong Kong doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.