Mass/30th is a mile away from the nearest Metro (Dupont Circle) so cab is your best option even if you take the shuttle into DCA. Cabs are tricky though coz you have to jump on I66-E to get into the city and HOV-2 expires at 0900 after which 66 becomes a parking lot. If you take a cab out of IAD at 9am (giving you 20 mins to disembark, mobile-lounge and find the taxi stand), you will hit 66 right when it's still congested. But an hour should be enough time to slog through that and get into the city. Also, if you enter the city right at 9:30, Rock Creek Parkway is the fastest way to get to Mass/30th (5-10 minutes; no lights) but it only becomes bi-directional after 9:30.

Friday morning traffic is usually very light, surprisingly, which always leads to a miserable afternoon rush hour (I telecommute most Fridays).