A woman places the moch dachuk from just before shekiah (sunset) until tzet hachochavim (when the stars come out). She can check the time of sunset or a calendar that includes daily zmanim for assistance in determining these times in her geographical location.

In Israel, this interval is generally about 20 minutes. In many communities outside of Israel, the custom is to wait about an hour; however, women who tend to bleed with the moch can remove it after 20 minutes.

One should avoid leaving the moch in beyond the prescribed time, as this can lead to irritation and bleeding.