From age 11 on, it was probably once a week if that (or as long as I could manage). Even tried showering in the dark, but it freaked my mother out. I would get literally nauseous being naked or looking or feeling myself naked. The whole ordeal: from peeling off the clothes and the layers of spandex I used to bind with to getting in the shower, cleaning something out of a horror movie, to getting out and putting all those layers on again - was like climbing Mt. Everest. I held out as long as I could.
When I was a junkie, it was almost literally never. Months at a time in between. Except when I felt like going out and getting laid. I kind of enjoyed the rank crustiness, but a partner might not of.

After T and top surgery, you can't keep me from the shower. I shower or rinse off multiple times a day (don't use soap every time though). I never knew how good water felt until now. I can't stand feeling dirty or sweaty. Never bothered me before. No matter how bad it got. Weird.