So I’m a cis man and I hope I’m not intruding and hope I’ll be helpful posting my take. I’m not taken to casual sexual relationships personally as I’m Asexual but if I were in your partners shoes I’d want to know in much the same way that I’d like to know if someone was a virgin beforehand. Its not something that would make me not want to hook up necessarily but I can imagine there are things that I could do differently that would make the whole experience better for both of us if I did know. That being said I completely understand the desire to move past that part of your life and I haven’t personally been in a relationship with a Trans person before so please take this with a massive grain of salt. Good luck, I hope everything works out for you