I dug up the instructions for the Barium Enema Prep that my Mom went through at 14
I also get some of this from talking to her younger sister who remembers it well and from her then-bother, who has now transitioned to female, and who also remembers it though was never quite as close to her as little sister
She ate a light breakfast the day before and went off to school like normal.
Her Father came and took her out of school at the beginning of lunch to be sure she stuck to the liquid diet from that time on, Not sure whether she ate between classes but she took this seriously enough that I want to believe she didn't.
1:00 Pm her father kept trying to get he to "Drink all the water you can stand!"
3 PM Fleet enema in Simms position retained as long as possible. Not sure how long that was but I understand it was well past the 5 minutes on the label.
4 PM drank a full bottle of magnesium citrate and just stayed in the house, near the bathroom.
5:30 The liquid expulsions stated Every 20-30 minutes .
7:00 PM, with the expulsions from the Magnesium Citrate still going on, 20 mg oral bisacodyl
12:00 AM The bisacodyl kick-in happened and she was as her sister put it " Like peeing out her butt!" meaning essentially clear at that point.
1:30 the constant expulsions had stopped and the liquid coming out had gotten a much lighter yellow
After that she did catch a few hours of sleep
He father woke he up around 4:30
4:45 Took the suppository with apparently a little "help" from the younger sister. That's who she trusted, I guess.
They left about 6:30 for thew 8 AM appointment