BA 349 then DL 4 at Heathrow
Nice → London → New York JFK
Timetable, London time
21:05BA 349 from Nice at the gate
16:35DL 4 to New York JFK leaves the gate
19 h 30 apart on the timetable, overnight
DL 4 leaves 19 h 30 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.