Philadelphia and New York share the same timezone year-round. When it's 12:00 PM in New York, it's also 12:00 PM in Philadelphia. Both cities observe DST on the same schedule.
Both cities use Eastern Time (EST/EDT, UTC-5/-4). Philadelphia is only 95 miles south of New York City.
Any time works! The Amtrak takes about 90 minutes between the cities, and NJ Transit/SEPTA also connect them. Many people commute between the two.
Philadelphia is America's 6th largest city and was the nation's first capital. The pharma industry, universities (UPenn, Temple), and healthcare are major employers.