My estrogen was in twice-weekly shots, and when I asked my doctor why they prescribed that I take them Wednesday evening and Sunday evening (clearly not exactly the halfway point in a given week, it was an every third day, every fourth day schedule) I was told there was still residual
estrogen from the last
shot even by the fourth day. Not so with prometrium, it fades quickly out of your system, they were definite that I had to be pretty much to the hour and minute on those. You're good.