After a clean hefsek tahara and moch dachuk are completed, one must count seven clean days in preparation for mikvah. Seven days are counted according to the Jewish calendar day. This means that night precedes the day. The shivah neki’im start on the night immediately after the hefsek tahara is performed, and end at nightfall of the seventh day. The eighth night she can go to the mikvah.
From the onset of shivah neki’im, after a clean hefsek, a woman should wear white undergarments. Wearing white allows the woman to notice any bleeding that may occur. If a woman finds herself spotting at the beginning of the shivah neki’im, she should consult a rabbi about putting on a pad to help avoid problems of ketamim.
If she forgot to put on white undergarments, the shivah neki’im are still valid, as long as she checks what she was wearing and finds no stains. She should switch to white undergarments as soon as they become available.
On each day of the shivah neki’im, the woman does two bedikot, one in the morning and one in the afternoon. If a woman missed a bedikah, the shivah neki’im are still valid, as long as she did at least one bedikah on both days one and day seven. If a woman finds it difficult to do bedikot, either because they cause her pain, or because she has a hard time getting clean bedikot, a rabbi should be consulted.