Join Date: May 2004
Location: formerly Gold now Diamond, formerly MSY, now LAX, formerly NW, now DL
Programs: Hyatt Plat, Hilton Gold, SPG Gold, Delta Diamond/1MM
Posts: 4,725
You can wait for as long as you want to select your benefit. It does take up to 24 hours before you get them so there is a chance that you might miss the upgrade seat....
FYI, AMS lounge agents are good at getting you upgraded with GUCs too