Philadelphia is 9.5 hours behind Chennai
Best overlap: 5:30 PM to 6:30 PM in Chennai is 8:00 AM to 9:00 AM in Philadelphia.
Schedule calls for 5:30 PM to 6:30 PM in Chennai — your colleagues in Philadelphia will be online from 8:00 AM to 9:00 AM. Philadelphia is 9.5 hours behind Chennai, so you only get about 1 hour of overlap a day — worth locking in a standing time like 5:30 PM in Chennai (8:00 AM in Philadelphia) before it slips. Because Philadelphia and Chennai don't both observe daylight saving, plan to re-check the overlap around March and November.