Since you performed one bedikah on Friday in the afternoon, you may count that day as day 1 of your clean days. Therefore you may continue with your original count and immerse on Thursday night as scheduled.

While ideally one should perform 2 bedikot daily throughout the seven clean days, the absolute minimum for a valid clean days is a hefsek taharah and one bedikah each on days 1 and 7. We strongly advise against performing the bare minimum number of bedikot except in a case of great need. However it is important to know that if you missed any of the bedikot during the clean days, as long as the minimum has been performed your clean days are valid and you may immerse as scheduled.

Please feel free to get back to us with any further questions.