While a hefsek taharah is preferably done in the late afternoon, closer to sunset, a thorough bedikah in the morning may count as your hefsek taharah as well. You may begin counting your seven clean days the following day.

There is an exception to this rule when you do your hefsek taharah on the same day you began bleeding. Practically this doesn't have much relevance since bleeding generally lasts more than one day and you need to wait until the fifth day anyway before performing the hefsek taharah. However, in a case where you were in the middle of your seven clean days and a new blood flow started, an early bedikah on that same day would not suffice.