Mazal tov on your upcoming marriage!

You are correct that you should wait to immerse shortly before your wedding. If your wedding is scheduled for a Sunday evening, you may plan to immerse no earlier than Wednesday night. (In some communities, a kallah immerses at night like other women. In others, she has the option to arrange with the mikveh to immerse during the day – in your case, on Thursday or or Friday morning.)

You should plan your hefsek taharah for a week before your scheduled immersion (i.e., for a Thursday night tevilah, your hefsek should take place on the previous Thursday afternoon before sunset).

There is nothing you need to do from the time your period ends until you perform the hefsek.

You did not mention whether you are hormonally manipulating your cycle before the wedding. If you are taking the pill, be sure to continue taking active pills until after you have consummated your marriage. If you scheduled your wedding based on your natural cycle (i.e., a few days before your next period) it seems as if you may be cutting it a bit close (depending on the length of your cycle). In this case it may be worthwhile discussing with your doctor taking progesterone pills short term for a few days before your wedding until after you consummate the marriage to make sure you don't get your period early.

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

B'Hatzlacha!