To calculate the first period date of every month after your marriage on May 17, 2023, you can follow a simple method. Start by noting down the date of your marriage and then add one month to it. For example, if your marriage is on May 17, 2023, add one month to it which will give you June 17, Now, subtract the day of your marriage from this new date (June 17 - May 17 = 1). This will give you the number of days you need to subtract from the first day of each month to get your period start date. So in this case, your period start date for every month would be on the first day (1st) of each month. Repeat this calculation for subsequent months as well.