Unless the women is on a big cycle with a bunch of test an AI like arimedex would be pointless. An AI stops the conversion of testosterone into estrogen(E) by blocking aromatase. Since women have very little test this is not how women produce E. They produce E in their ovaries and the best way to control that in the natural or close to natural woman would be with a SERM such as was previously mentioned, Nolvadex.
For men sure if they are on a bunch of test then it can be affective for them in controlling E sides. Anytime of day, it does not matter.