I'm landing in JFK off an AY flight from HEL at 3:55 PM. I need to buy a separate JFK-ORD ticket. What is the earliest advisable time for a flight? I'm thinking after 6 PM is safe for AA, maybe 7 PM if I end up using another carrier (the DL flight looks to have the best schedule at the moment, but this is in November so things could change). I have GE and PreCheck and am flying J on AY.