I just got home last night. Both days we were at DCA the fastpass lines were not opened until 8am. And wow were they long! The first time I got in line, it was 7:45, I had jumped out of the standby line because the Racers were still not running. I got my fastpass at 8:10, for 12:10 return. We went to use it about 12:30, got through quite quickly, only to have it break down as soon as we were buckled in. So they gave us new fastpasses and made us leave.
When we went to get on again, mid afternoon, the fastpass line was full and outside of the queue area, so we left again. About 7pm we tried again, and this time were inline and off the ride in 20 minutes.
The 2nd day, I was in the fastpass line, well past the Disney Junior show, got my passes at 8:15 with a 10:20 am return time. That day they will had fastpasses available at 10am, which really surprised me. Again, when we returned to ride this time, about 20-25 minutes from getting in line, till walking out the exit.