Had my first this week also. Worst part was being the only medical person in the room NOT getting paid to be there.
We in the medical realm are terrible at actually following medical advice.
And ever since I referred to the colonoscopy consent form as signing over "Drilling Rights", they discourage my contact with conscious patients.
That said, here's my advice: follow the prep sheet; 'cause if you don't, they won't be able to see for s***t and you'll have to it again.
Enjoy that last big BBQ meal at noon three days before the procedure, then avoid meat, lettuce and corn. Hit smoothies and soft foods for another day and a half, then follow the clear liquid diet for the previous day.
Pick a flavor of Gatorade / Crystal Light that you hate for the prep mix; you're not drinking it for the flavor and there's no sense in ruining it for the future.
Brian is right about the eating afterwards; your appetite and guts will NOT be in synch for at least a day. Avoid spicy, greasy and dairy foods til at least the next day.
Be prepared: Grab a fairly plain turkey sub sandwich (no mayo/mustard) on the way there; tell your driver to have it ready when you wake up. You're gonna be hungry and tempted to eat what you shouldn't if you roll out of there with an empty stomach.
(You're also not supposed to travel after the procedure, but I had a funeral in Florida to attend and went from a tube in my butt to vice versa the very next morning).
Congrats on the courage and clarity of your decision; a close relative waited 10 years too long and now has a colostomy and a chemo port.