Shenzhen is 13 hours ahead of Montreal
There is no standard 8-to-6 overlap. Someone joins early or late.
When Montreal starts work, Shenzhen is already winding down or offline — the 13-hour gap leaves no shared window. Default to async and only schedule live time when it genuinely needs a conversation — then make it count. Seasonal note: Montreal uses daylight saving and Shenzhen doesn't, so double-check the times in your own months — they can move by an hour.