Philadelphia is 16 hours behind Wellington
Best overlap: 8:00 AM to 10:00 AM in Wellington is 4:00 PM to 6:00 PM in Philadelphia.
The overlap falls at 8:00 AM to 10:00 AM in Wellington, or 4:00 PM to 6:00 PM if you're in Philadelphia. Just 2 hours of shared hours means there's little margin — set 8:00 AM in Wellington (4:00 PM in Philadelphia) and start promptly. In this window Wellington and Philadelphia are on different dates, with Philadelphia on the previous day.