I would leave Philadelphia about five thirty or six (Ben Franklin Bridge, Admiral Wilson Blvd, NJ38 and then NJ73 to the New Jersey Turnpike to try to hit the Staten Island Expressway about 730 when all the traffic has (should have) died down. Doylestown or anywhere in Central Bucks would be 15 minutes closer and Horsham near the Pennsy Pike about 1/2 hour.
Depending on the flow of the NJ Tpke, I would probably take the Outerbridge Crossing at exit 10 and the West Shore Expressway up to the SI Xway. From that point you should make JFK in about an hour using the Verazzano Narrows Bridge and the Belt Parkway around the bottom of Brooklyn and arrive about 830 give or take.
But you can give a lot when the NY traffic does not behave and an extra hour on that route is far from very unusual.