Washington, D.C. is 13 hours behind Shenzhen
There is no standard 8-to-6 overlap. Someone joins early or late.
Shenzhen and Washington, D.C. are 13 hours apart, and that gap is wide enough that their normal 9-to-5 workdays never quite touch. If you meet regularly, fix one off-hours slot and rotate it between Shenzhen and Washington, D.C. so the burden doesn't fall on one team. Finally, Washington, D.C. observes daylight saving and Shenzhen doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.