When a woman forgets to perform any bedikot on the first day of her clean days, she typically loses that day. In other words, in your case, the hefsek taharah on Tuesday still counts, but mikveh night is delayed to Wednesday night because your first full clean day was Thursday (i.e., Wednesday night through Thursday day).

In rare cases of great urgency, there are sometimes other factors that can lead to leniency. If yours is an urgent situation, please write back with details of the situation and of whether or not you performed a moch dachuk.

In the future, we recommend incorporating the first bedikah of your day into your wake-up routine.