Hi, CaptainWildRose - can I ask for a quick clarification? For transition, do you mean HRT, bottom surgery (and what kind: orchiectomy, penectomy, vaginoplasty, labiaplasty, clitoroplasty?), or both? I can't personally help answer this question either, but I have some potential resources, but what you mean by transition could impact the answer, so I just want to make sure before I try to deep dive my ref collection!
EDIT: Ah, I found the post I was thinking of, which (includes a lot of nsfw links!) is a masterpost of sex/masturbation/dating tips for transfem folk
. None of the links directly answer your question exactly (which is likely subjective anyway!), but it may still be of interest! It does include some talk of how to explore a changing body and different masturbation techniques, which seems the most relevant to your question here. ^^
A mod at that same blog also mentioned they're a part of a few Facebook groups for post-vaginoplasty trans women where they talk about re-learning their body. You might try searching those or asking the tumblr transgenderteensurvivalguide if they can provide you links to those groups (I would send off anon if you have a tumblr and request to talk privately regarding that) if vaginoplasty is something you're thinking about.