Wellington is 4 hours ahead of Shanghai
Best overlap: 8:00 AM to 2:00 PM in Shanghai is 12:00 PM to 6:00 PM in Wellington.
Both teams are at their desks between 8:00 AM to 2:00 PM in Shanghai and 12:00 PM to 6:00 PM in Wellington. Plenty of room to work with: 6 hours of daily overlap means you can prioritise people's preferences over the clock. Note the seasonal wrinkle: when Wellington is on daylight saving and Shanghai isn't, the gap between them grows or shrinks by an hour.