For some patients there is a delay in colonic activity up to 2-4 hours. Lets first go over the fundementals: The standard model for bowel preparation is “split prep model” where you take half the prep the day prior and half the prep 5 hrs prior to the procedure. If you take the first half the day before, and do not see any colonic activity within the ifrst two hours, then go ahead and finish the 2nd half of your bowel prep the day before your procedure. Now 5 hours prior to the procedure you should take a product called “magnesium citrate” ( a liquid solution, 10oz bottle). This additional component should optimize your bowel preperation.