IIRC, my food intake wasn’t restricted until 24 hours prior... then, starting at 10 p.m. the night before the procedure... my special night with NuLitely... ahhhh, memories.
BTW... the colonoscopy procedure itself isn’t a big deal. Once you’ve gotten through the “cleansing” stage, the rest is relatively easy.
Reading thru this it sounds as if there are different preps. Must depend on how much your doctor hates you. Mine must have only mildly disliked me.