Join Date: Jan 2005
Location: New York, NY
Programs: UA, AA, DL, Hertz, Avis, National, Hyatt, Hilton, SPG, Marriott
Posts: 10,111
2 hours before the first flight of your itinerary (in one direction) is a good rule of thumb, although I'm not sure of the precise policy. I have always been able to add companions to the u/g list for connecting flights at my point of origin.