Maybe send an email if you have their email address? If you have difficulty starting the conversation perhaps you could ask them to lead. You could tell them you have been experiencing things you think are important to mention but have trouble bringing it up. Maybe then they could ask questions that would ease into it a little more instead of a straight out confession which could be difficult, especially with someone new.
Even if you can't tell them right away (or can't bring yourself to bring the note out of your pocket) at least tell them what is up that way they can hold you accountable when you are able to do it and it doesn't just get swept under the rug.
Best of luck! Starting with a new T isn't easy, but if you get off on the right foot with honesty and openness there is the potential for it to really help.