Calgary is 15 hours behind Shenzhen
Best overlap: 8:00 AM to 9:00 AM in Shenzhen is 5:00 PM to 6:00 PM in Calgary.
8:00 AM to 9:00 AM in Shenzhen is when Calgary is also working, at 5:00 PM to 6:00 PM their time. The overlap is tight at roughly 1 hour, so protect it: 8:00 AM in Shenzhen / 5:00 PM in Calgary is your safest recurring slot. Watch the date, too: while it's still the workday in Shenzhen, Calgary is already on the previous day. The window above shifts seasonally: Calgary keeps daylight saving while Shenzhen ignores it.