My sister had one maybe a year or 2 ago. I remember the prep being terrible, and then she said they wouldn't let her go afterwards until she farted. She said it was hilarious, a bunch of people all groggy and saying the silliest things, all lying next to each other merrily tooting away. Actually, she didn't know what she was saying when she came into the recovery area. She yelled very loudly "I can't leave yet! I need to fart first!" The recovery area was all from people who had colonsocopies, so it made for an interesting time.
I had a routine colon in Feb at UMASS MED CTR...big HUGE facility. Naa, no one was telling anyone they had to fart before they left....
Anyway, I did the miralax. I made it up the night before. Chilled it is absolutely fine.
My experience was that they had me drinking all this miralax and combined with the dulcolax tablets was way to much for my system.
I did indeed go to the procedure
(on a day in Boston that we were having one of the worst ice storms of the winter). I had to go to the appt. After the prep from the day before, I was not doing this again.
Well the MD's did the procedure but I
(was not cleaned out enough) 
Despite following all the directions....
Anyway, I was told everything looked fine BUT I should have the procedure done again to just be sure. So I essentially need a 2 day prep.
After the procedure I was quite nauseous.

They gave me companzine and DH took me home.
OP, I am scheduling my appt. again and will do the 2 day prep this time. No worries, you will be absolutely FINE. This is an important procedure for Peace of Mind!!!
They did tell you that you need to have a driver take you home???