We had our surgery the same day! I was worried about constipation too, but instead was shocked to have a completely liquid bm, sorry to mention it. I wasn't expecting that - maybe because I was on liquids only and so much IV in the hospital? I think if you are worried about constipation, keeping up with plenty of water is the way to go.
I have a date of Jan. 16, at NYU hospital, assuming everything works out with insurance (things are looking good so far!) I started my fast today, and I don;t feel so well but I AM DETERMINED. Major winter storm coming through here tomorrow but I;m going for mypre-op testing and nothing is going to keep me from doing that!