I don't know the answer. I filed my FDC (federal district court) materials pro se, but after that I was able to find an actual attorney before it was time for the filing of briefs to begin. If memory serves, it took the SSA about 5 months to respond to the complaint.
To others reading this, this is why it is important to try and get an attorney who can take you through the FDC level. It is not impossible to do on your own, but sometimes it is difficult and/or confusing even with the instructions provided online, and deadlines are vital. For me, there was very little chance of doing it correctly and effectively while battling severe depression and anxiety. After so many rejections, I was lucky (and grateful) to come across a federally-admitted SSDI lawyer who was willing to step in so late in the game.