My colonoscopy is tomorrow and I took my first dose earlier this evening. Great tips on these forums, they helped me a lot!
I rarely get nausea, but I did get mild nausea about half way through my first liter. I chose not to chug it, and instead took healthy sips from a straw and I think that helped keep the nausea at bay.
Definitely chill it, like many have suggested. The taste isn't pleasant, but it's not disgusting. Just try to keep it off the tongue as much as possible. It wasn't that bad. I highly recommend a chaser if you can't get over the taste. Even water will do the trick.
I suspect I have IBS-D, so for me I felt the first BM about 20 minutes after taking my first sip. I only had 10 ounces in me at the time. Bathroom trips were at their most frequent between hours 1 and 2. It settled down a lot after that. After 3 hours I didn't have to make any more trips.
The prep is supposed to be the worst part of a colonoscopy, and overall it wasn't that bad. Take in all the advice on these forums and make the choices that sound best for your body.