BA 92 then FB 852 at Heathrow
Toronto → London → Sofia
Timetable, London time
05:50BA 92 from Toronto at the gate
17:55FB 852 to Sofia leaves the gate
12 h 05 apart on the timetable
FB 852 leaves 12 h 05 after BA 92 arrives on the timetable: more than half a day, so not a connection we count.