It looks like they are going by the finger printing appointment date, and not the date on which the fp is done (for early walk-ins). Its pretty clear now that completing finger printing earlier than scheduled has no advantages.
Really? (Please see my timeline below)
However, I agree this whole 'fast processing' thing may be moot if I end up with an interview within 90 days of applying as I won't be Oath Eligible until Feb 2010.