My first colonoscopy, I made the same calculation (just about getting home, no stops). My boss, who knew I was going to be out for the next two days and had already been through his own procedure, stopped at my desk after lunchtime and asked, “What the hell are you still doing here?” I explained I planned to work another hour or so, take my first purgative dose, then head home. Plenty of time! “NO! While you are drinking that hellish concoction, you are never — NEVER — more than ten steps from a toilet. Trust me!” I went home. He was correct.