I started the day I left for home, which was 9 days post-op. I went back on the same dosage as before, but it was super low (within the range of what's used for menopausal cis women) so my endo figured why not see how that worked out. All the follow-up tests she did at 3 months post-op were perfect, so we stuck with that so far.
I now tell other doctors I am in surgical menopause and on HRT, which is 100% true; I got the idea from a friend who had a hysterectomy at around the same age, and has had to say the same thing. It's uncommon for a mid-30s woman to be menopausal, but not unheard of.