When I was first being introduced to a interim therapist, I wrote an email stating my diagnoses, symptoms, struggles, needs, wants, and goals. Well he offered L to work with me. L read my email and said she instantly knew she wanted to work with me. During our first session, I gave her a timeline of all my mental health events. That helped her a lot too.

Anyways, I would highly recommend writing out important things you want your potential T to know and giving it to them in advance. Just get it out of the way. I am not saying tell them your secrets. Wait until you've developed a relationship for that, imho. But everything else, let them know. If they can't accept you after that, good riddance. But if they do, you can start working on your issues right from the start.