ILR Residency Qualifying Period?

My Wife arrived in the UK from Brasil on a Fiancee visa on the 12/07/2009, we got married on 11/09/2009 and were given further leave to remain until 29/12/2011. Does the 2 year residency qualification period start from a) on the date she arrived in the UK (12/07/2009), or b) 29/12/2009 (2 years from expiration date of FLR?) Any help much appreciated, Steve

b) 29/12/2009. She may apply for ILR no sooner than 28 days prior to 29/12/2011.