I think it began much earlier. He started that "tomgirl" nonsense in 2011, but he wore his first sports bra back in 2009 upon Kasey's suggestion (Chris was worried that his manly bosoms would jiggle when he ran as Kasey was encouraging him to exercise).
Maybe I'm naive (my LEAST FAVORITE word), but I don't see a lot of manipulation back then. For one thing, I don't think Kasey was smart enough to manipulate anyone - even a slow-in-the-mind like CWC. But beyond that, I think that his sports bra was the first new, properly fitting garment he ever had, and that fused some things in his broken brain.