I think a general set of boundries needs to be discussed at the beginning, but like JustShakey said, they can be fluid and adapt to where the client is at. I know I asked my T for her boundaries at the beginning because I always get anxious about crossing them, especially when I hit a crisis point. I have asked her more than once to reiterate the boundries for me so I know where I stand. I think though I am generally more worried about boundaries than my T is because I alwasy worry about beign a bother.