I'm not sure about the exact number, but the half-life of estradiol is, I think, 12 hours. It means that once it's done absorbing, the estradiol level will have peaked and gone down to half the peak's level within 12 hours. With that in mind, I think the level would be pretty low after 24 hours. If a steady hormone level is desirable (and while I'm not sure, I think it is), then doses should probably be spread out more.
Now whether you take it two, three, four or whatever times a day is up to questioning, but one is questionable in my opinion. When my dose was increased from a number divisible by two to a number divisible by three, my endo said it didn't matter if I took them in one, two or three shots, if you're curious. But I wouldn't listen to him. Because nothing usually matters to him, not even common sense.
Anyway, even though your endo hasn't dealt with many trans people, she's dealt with hormones. If she's a good endo, with the product's half-life, desired levels and knowing whether it's desirable to have more stable levels rather than rare, steep spikes (which she should probably know, but you can research to make sure), she'll be able to prepare a treatment schedule properly. I think you can trust her with that.
Oh yeah, just one thing. Being in the female normal levels isn't enough. And having just enough estradiol to see some change isn't either. In terms of numbers, what should be aimed for is the higher normal female values, in the upper third of the normal range maybe. Upper half minimum. Because the lower half is close to and somewhat overlaps with the male normal/not worrisome levels.
In terms of effectiveness, I personally think the most sensible approach is, once testosterone is appropriately assassinated, to gradually increase the dosage, until no additional desirable effects are noticed. Within reasonable bounds, and being careful of the placebo effect, of course.
I think too many doctors are overly prudent by going with "the lowest dose to achieve results", while the principle should actually be to go with "the lowest dose to achieve the DESIRED results", and the desired results just so happen to be the maximum results. Many will feed you with "you have a limited number of estrogen receptors, and at some point they'll all be busy and adding more estrogen won't do a thing", but they assume a bit fast that the patient is already at the limit where all receptors are busy, having never tried a higher dose.
Orihime: Actually it depends on the endo. Apparently, some, even with antiandrogens, believe it's more appropriate to use amounts between once and twice the normal female range. Maybe it's because they want to mimic puberty and that in puberty hormone levels are higher? Maybe? I don't even know if puberty levels are higher than adult levels. Seriously, I wish HRT were less of an endo opinion thing, so we could understand things properly and wouldn't need to speculate like I did above.
