Wellington is 16 hours ahead of Philadelphia
Best overlap: 4:00 PM to 6:00 PM in Philadelphia is 8:00 AM to 10:00 AM in Wellington.
The overlap falls at 4:00 PM to 6:00 PM in Philadelphia, or 8:00 AM to 10:00 AM if you're in Wellington. There's roughly 2 hours to share, so keep agendas lean and meet at 4:00 PM in Philadelphia (8:00 AM in Wellington) to use every minute. The two cities aren't on the same date during this window — Wellington runs the next day from Philadelphia.