Yeah, you won't get any sort of externally visible changes from a single dose, but for some trans people that first dose can still be a life-changing experience.
They don't warn you about it in the informed consent documentation, but for me that first day on HRT brought on an almost overwhelming feeling of gender euphoria. It was like a part of myself that had been missing since puberty finally fell into place. The weight of 25 years of repressed dysphoria fell from my shoulders and I couldn't stop smiling, couldn't even walk across a room without breaking into a little dance.
It took the better part of a week to start seeing some physical changes, and that was mostly in skin texture.
that's definitely part of it, but sex hormones interact with* neurotransmitters and the mental/emotional stuff tends to hit first, before any physical effects take place.
Not countering what you experienced, but sex hormones are not neurotransmitters. There may be some interactions with the neurotransmitter system but it they are not themselves.
I think that part of it, for me at least, was that it felt like everything shifted and all of a sudden my brain was finally running right for the first time in my life. It’s like it was already wired to run on estrogen and I was finally giving it what it needed.
You absolutely can get some emotional benefits from the first dose before the physical ones start. I felt much more calm and less heightened emotions after my first dose of T. A welcome change having dealt with PMDD for years.
It does! But I should mention that this experience isn't universal.
Some trans folks don't get the day-1 giddiness at all, instead finding that their baseline mood improves steadilly over the first few days or weeks of treatment without a period of euphoria.
Another common experience is a period of mild depression around 6-8 months in. For me, this was similar to the teenage moodiness of my first puberty, though much milder and less "wrong"-feeling.
Tbh, I'd be tempted to say "go for it!" if it weren't for the medical liability. A doc would want to check your hormone levels before prescribing estradiol just to ensure that there aren't any risk factors present.
The odds of one dose fucking you up are very, very low but not zero.
There's a reason E is normally prescribed with a testosterone blocker. Small doses of Estradiol will do next to nothing if there's still a natural level of T flowing through your system.
I've still got my "normal" levels of testostetone, but I'm taking finasteride to keep it from affecting my hair follicles while the estradiol does its work softening my skin and plumping up my chest.
I probably could be a lot more feminine by this point if I had a full-spectrum anti-androgen like spironolactone or cyproterone acetate, but that's not my transition goal. I'm actively seeking an androgynous appearance and itty bitty titties, so estradiol monotherapy with finasteride is working just fine for me.