The small bowel can empty part of it's contents into the large bowel as often as every 20 minutes. Likewise the stomach can empty part of it's contents to the small bowel about as often, though not usually at the same time.
As a result, what I do for a system cleanout is this:
I start the day before, at lunch. Eat WHAT I normally do, but half as much. Then nothing but liquid after that, No alcohol, no dairy products.
I also prepare the soapsuds in the shaker bottle if that's not already done.
Usually I sleep fairly well.
Upon awaking I take 6 generic Dulcolax tablets. The purpose of this is to clear the small bowel, which is the hardest part to clear
I then go about my early routine. Feed the kids, walk the dog, get the hubby or my Dad or his Mom to take the kids for the morning so I'm alone. Doors locked, cell phone off, laptop off.
I mix up a 3-qt Epsom Salt and soapsuds enema. Go through the usual hanging,mixing, positioning, injection retention etc that I have described in detail in earlier postings. I then start taking soapsuds-only enemas until I get to a clear return, as i have described before. Typically the bisacodyl will "kick in" Sometime after the third enema in the series. Though I HAVE had it kick in while retaining the third enema, and I have had It kick in after the fourth enema, so you can never quite tell
That usually pretty well clears the system. Sometimes, If I have any doubts, I wait an hour after that and drink a magnesium citrate just to be certain.