Leaving will be immediate. I already know he has no place to go, and so does he. Where he would go and how, would be his problem. I think I already said something to him some time back, that you should be thinking about Plan B, if this doesn't work out.
I had thought about him using more than the prescribed amount of his pills, but he hasn't ran out of any before refill time. The drug test I bought (yes, I already have one here) is specifically for meth, this is his DOC and what I would be looking for.