I did estrogen monotherapy for about 2 months earlier this year. Quite frankly, the only changes I noticed was an immediate and significant increase in nipple sensitivity+size, and a reduction of nighttime erections. Other than that I didn't notice any of the early changes which I had been lead to expect within the first few weeks: no emotional differences, no reduction in skin oiliness, no changes in body temperature, etc.
For what it's worth, I was taking 1.4ml/week of 40% estradiol enanthate without any antiandrogens, am in my early 20s and have a very low body mass.