@jaderobin Maybe that scene took place around the middle of the month or something? The raws say 来月 (next month), not 1ヶ月 (1 month of time), so it's possible that "next month" is two weeks away. I really don't know enough about the general practices for HRT in Japan to say that they don't just do it monthly though or at what concentrations they typically prescribe.
With great sadness I have to report that she is probably getting underdosed, I suspect that they are using a regimen similar to the one in "Alteration of ACTH and Cortisol Levels After Estradiol Valerate Treatment in a Male Subject With Gender Dysphoria: A Case Report" - where they give her 10mg EV every 3 weeks. (EV half life is like 4-5 days) probably to simulate the levels that the average cis female would go through (where you have a single big bump once a month and during the rest of the month you have nothing).
Given that she is starting HRT after SRS, the horrible gatekeeping that she went though, and the multiple reports that I heard from japanese trans girls that are being told to take premarin by boomer doctors I don't have high expectations.
It is possible to take estrogen less often, by using implants (~6m-1y?), EUn (~every 2 weeks), or Polyestradiol phosphate (~monthly) but all of these methods are quite rare.