B6 519 then DL 825 at Atlanta
New York JFK → Atlanta → Las Vegas
Timetable, Atlanta time
08:37B6 519 from New York JFK at the gate
20:45DL 825 to Las Vegas leaves the gate
12 h 08 apart on the timetable
DL 825 leaves 12 h 08 after B6 519 arrives on the timetable: more than half a day, so not a connection we count.