BA 521 then BA 740 at Heathrow
Firenze → London → Geneva
Timetable, London time
14:00BA 521 from Firenze at the gate
13:50BA 740 to Geneva leaves the gate
23 h 50 apart on the timetable, overnight
BA 740 leaves 23 h 50 after BA 521 arrives on the timetable: more than half a day, so not a connection we count.