Or, after dinner, or after your coffee (also remember coffee will atually dehydrate, and also don't forget that coffee contains K). I always limited coffee to one a day max while on D. Water is much better (but boring) to drink.
Coffee doesn't dehydrate.The caffeine in coffee will make a healthy person urinate more, but it won't cancel out the amount of fluid in the coffee. It won't dehydrate someone who doesn't pee. If it did, I'd be drinking coffee all the time!