At the risk of getting run over by the bus, I'd bet on at the gate day of.
Code:
0 Connections
UA 956 0 SFO
06/28/06 07:55AM JFK
06/28/06 04:21PM 757 BS F7 C8 Y2 B2 M1 E0 U0 H0 Q0 V0 W0 S0 T0 K0 L0 G0 P4 A4 D7 Z0
Looks like the seat maps and buckets are in parity, with the exception of numerous missing seat assignments in Y.
Pat