I heard of a case kind of similar, but it was a marriage based i485, the wife's FP was scheduled for a month after the interview, the officer notice this during the interview and sent her to the ASC that was in the same building, she actually didn't have a interview, they just ask general questions to the husband and the case was approved a week later. But in your case I would try to go to an ASC with the interview notice and try early FP (that's what I would do).