http://www.dcunited.com/news/2012/10/dc-uniteds-playoff-picture-0
Wild Card Match (Oct. 31 or Nov. 1)
Eastern Conference Semifinal, Leg 1 (Nov. 3 or Nov. 4)
Eastern Conference Semifinal, Leg 2 (Nov. 7 or Nov. 8)
Those are all the possible dates. And I've heard the same as the guy you referenced, that depending on final standings we'd play at home 31st, 3rd, or 7th.