tough one
As far as I know, that is not something you can change with just the regular options in XP. The only thing that might accomplish that is a custom logon script.
With XP you have to choose between automatically loading one profile, or showing the logon prompt. To have a "wait time" before the one user is logged on by the system sounds pretty esoteric.
That said, here is a
link to some articles in the Microsoft Knowledge base you might find informative on this topic.
Sorry I don't have a quick answer!
Check back here if you have any more questions.