If I were a mental health patient, I don't think I would like to have someone working with me that had a mental health issue and didn't tell me. I think it would only be fair to disclose. Why not? You would have something in common with your clients, and you wouldn't be hiding it. If they like you, they will give you the job, BP or not. If they find out you have BP after the fact, they may not be so understanding.