LX 319 then FB 492 at Zurich
London Heathrow → Zurich → Sofia
Timetable, Zurich time
14:45LX 319 from London Heathrow at the gate
10:00FB 492 to Sofia leaves the gate
19 h 15 apart on the timetable, overnight
FB 492 leaves 19 h 15 after LX 319 arrives on the timetable: more than half a day, so not a connection we count.