Well, Not exactly...
Once the FP is done, FBI investigates and reports the result to the INS. So, theoretically, if FP notice takes 8 months and the investigation takes longer than 4 months, then the FD will definitely affect the whole I-485 processing time. But, I\'ve seen some cases that were approved after one or two months since the FP dates. So, we don\'t have to worry I guess.