BA 631 then DL 4 at Heathrow
Athens → London → New York JFK
Timetable, London time
17:00BA 631 from Athens at the gate
16:35DL 4 to New York JFK leaves the gate
23 h 35 apart on the timetable, overnight
DL 4 leaves 23 h 35 after BA 631 arrives on the timetable: more than half a day, so not a connection we count.