Sounds like everyone agrees that you'll see T1 again as long as you're doing the DBT, but no one has set up an actual appt yet? If this is the case, I don't see why you couldn't email him and ask if he's ready to set up an appt for you. If he needs to talk to DBT-T first for some reason, then he could tell you that. I don't see anything wrong for taking the first step towards an appt instead of waiting for T1 to contact you.

I may be missing something here, but I don't see a problem with that. Keep it short and to the point?