Congratz on getting approved and getting ready.
The first week of Clear Liquids it was a bit rough. There is so much gas in your system from the surgery that every sip you take in requires what feels like 20 minutes of burping to get down lol. It is not really that bad but the first 3 days were kinda interesting. Make sure you run by walmart and get the Gas X strips. They work awesome!! Just remember to be proactive about it, dont wait until you feel the gas to take them like I did. Start taking them as soon as you get home even if you don't feel the gas as it will keep it from building up.
The first week wasnt bad as I was on the Liver Diet 2 weeks prior to my surgery (and during the 4th of July ) so I was use to liquids prior to the surgery. My wife made me this fabulous Cream of Broccoli Soup from scratch for my first day of creamy and I about cried lol.
As for the amount you drink, definitely start off on small sips and make sure it is warm, cold stuff that first week hurts. I just left Water bottles out on the counter room temperature, Gatorade at room temp, and in the mornings, get you a packet of Jello mix it with the warm water and drink it. It allows you to get some calories in so you heal a bit faster and feels good on your stomach because it actually coats it plus it is very warm. Camomile's teas work wonderfully too