Shenzhen is 6 hours ahead of Kyiv
Best overlap: 8:00 AM to 12:00 PM in Kyiv is 2:00 PM to 6:00 PM in Shenzhen.
8:00 AM to 12:00 PM in Kyiv is when Shenzhen is also working, at 2:00 PM to 6:00 PM their time. You get roughly 4 hours of shared time, so aim for the middle of that window to keep the call comfortable for both teams. The window above shifts seasonally: Kyiv keeps daylight saving while Shenzhen ignores it.