Women often find it difficult to prepare after the fast because they are tired and hungry, it is a late summer night, and twice as many women as usual will be using the mikveh (since there is no immersion on Tisha B’Av itself). Therefore, we recommend performing as much of the chafifah as possible on erev Shabbat, at least taking care of some more durable preparations, such as cutting nails.
Preparation for the mikveh is not viewed as bathing for pleasure and therefore your usual preparation routine is permitted on Friday (although not on Tisha B’Av itself). Concentrate on preparing and don’t spend extra time luxuriating in the bath. There is debate among halachic authorities about married women shaving body hair during the three weeks, so it is best to check with your rabbi about this.
Given the two-day gap, you will still need to refresh your preparations on Sunday night. However, the Friday chafifah should help to reduce preparation time after the fast. If you want, it is permissible to take a longer bath and/or shave immediately after the fast, since Tisha B’Av is postponed from Shabbat to Sunday.
You are allowed to eat before immersion, so long as you are sure to brush your teeth well after eating. Often, the mikveh will remain open later the night after Tisha B’Av to allow women to eat before going to the mikveh. If there is not time to eat at home, then pack something to take with you. We recommend checking in advance to see if there is a change in mikveh hours Sunday night.
Once you have completed your clean days, you may switch to colored undergarments and do not perform any further bedikot.
Please write back with any further questions.