I recently asked B'lo about this, and was told to hold on to additional documents and information until I received file number from the Buffalo office. I don't think you have to wait for the document request, although my guess is that if you send your additional information when you receive the file number and stickers in the AOR, you might *still* receive the document request as it might be in queue to be issued before your new information is integrated into your file..
I personally am going to send the additional information as soon as I get the AOR (which, fingers crossed, may be as soon as next week....) and am not going to wait for a document request, in case they don't request the FBI clearance until it is expired..