Originally, my two years spouse visa expired on the 28th of june 09. But my eligibility to apply for ILR started on the 11th of july 09, due to the fact that i delayed my journey to UK for about (41 days). Therefore, i was advised to send my application before my visa expired and, according to what i was told, my application was held untill my qualification date, 11th july ' 09. So with my calculation, my application took only 7 weeks, as it was granted on the 28th of august, and received on the 2nd of september.
Thanks, hope my explanation is cleared enough!
Best of luck