From everything I've read on this, hair follicles can store THC for up to 6 months. The longer you're hair grows out, the further back they can detect. Most facilities cut from 3-5cm from the scalp and trash the rest, which changes the detection period to about the last 90 days or so. Again, this is just what I've researched - I figure after 200 days and a haircut or two you're probably fine. Good luck man!