Sorry I can't speak for that time of month since I surgical menopause but I have a niece who is your age and she has UC ...When she was scheduled for he scope she begun the day before. She called her GI and asked the dreaded question. The nurse in turn called her and said the doctor had no problem doing it but if she was uncomfortable with that aspect of it he would glad delay it to the following week.
Sorry I couldn't be more helpful but I think if it is a concern you are having just call the office and ask what their protocol is in that situation..
Hope you get the answers before hand be well
I asked about that before my first one, and they told me that it was okay, and that I should just use a tampon/cup during the procedure. But you should definitely call and ask them about it, in case it's different for different doctors!