Hi Can/alb
From my experience, when there is a BFD on the file the officer might or not open it until the day S/he assigned to work on it. In case the officer requested documents, medicals or background check and at the arrival of those things at CHC s/he is forced to open your file and further review it even if it is not the BFD. In your case there was an interview which I believed went so well and there is not documents requested from you, they will probably wait at your BFD if vo is busy. But I strongly believe that all is well. Did the officer ask for your passport after the interview? Which could be an indicator that he or she was satisfied with your answers, Keep me posted I'd love to hear more from you dear. Stay positive and blessed.