It sounds like you've gotten some great advice. I'm new back to riding, but rode a lot before this hiatus. I've just had my first period since riding again and had forgotten about these "times". Now I remember that it really affected (affects) my cycling. I have a lot less energy and my back aches in the saddle, so I have to stretch and stand more. My solution was (is) to not do anything major those first two days. So, for me : use a super absorbent tampon and take light rides that last less than two hours so I don't need to change while out riding. I feel that I'm close to (peri-)menopause, so hopefully I won't have to deal with this for too many more years.