If you say it repeatedly, it becomes true. What logic did you use to arrive at this conclusion? Oscar was already at 147lbs weeks before the fight. He doesn't need to dehydrate himself to make the weight.
Freddy can tell it better than I can http://www.youtube.com/watch?feature=player_detailpage&v=CpxtKlVQqCU#t=27s
Going by why he didn't know about Rugged Man's interview with Floyd, it has to be just after that. I say just one and a half year....