Copenhagen is 6 hours ahead of Philadelphia
Best overlap: 8:00 AM to 12:00 PM in Philadelphia is 2:00 PM to 6:00 PM in Copenhagen.
Keep meetings inside 8:00 AM to 12:00 PM in Philadelphia — that maps to 2:00 PM to 6:00 PM in Copenhagen. Around 4 hours of overlap is enough to work comfortably, as long as meetings don't drift to the end of one team's day.