Specifically, you have asked for clarification regarding the time requirements for a biennial flight review in 14 C.F.R. § 61.56(c).
***
Based on the facts that you have presented, a biennial flight review accomplished on April 2, 2002, would not lapse until May 1, 2004.
2012 Harvey Interpretation (asking about the FR calculation). There are plenty more FAA references that use it
Several commenters wanted the FAA to allow for simultaneous training and checking, and to allow all SFAR training to satisfy requirements for the biennial flight review.
2008 Final Rule in the Federal Register dealing with the SFAR for type-specific MU-2 currency.
Those two were very quick to find. There are plenty more from after the change.
So the FAA is apparent not all that OCD about the language