UA 3907 then DL 2709 at Houston
San Francisco → Houston → Atlanta
Timetable, Houston time
13:20UA 3907 from San Francisco at the gate
08:05DL 2709 to Atlanta leaves the gate
18 h 45 apart on the timetable, overnight
DL 2709 leaves 18 h 45 after UA 3907 arrives on the timetable: more than half a day, so not a connection we count.