I weigh in the morning, as do most, because as you go about your day (drinking, eating, etc), the weight of those things you put into your body is added into the weight the scale gives you. So the morning weight tends to be more about what -you- weigh and less about what -you and the liter of water you just drank- weigh together.
If I'm weighing myself at home, it's first thing in the morning. I do my official weigh in at work (we have a medical scale) and that's usually around lunch time. I definitely go potty first though.
Morning here as well. I agree with animallover, I find the scale goes up a couple pounds if I weigh later in the day. I really don't know why, it just does!
I do morning cuz during the day the amount of food you eat varies and by the time you are up in the morning your body has usually gone through at least an 8 hour fast
I also weigh in the morning, before breakfast, after the bathroom. I find that my pjs are light enough that they don't make an ounce of a difference if I weigh with them on or off. So I weigh with my pjs on.
FYI, I just calculated this right now, so I figured I'd share with you ladies.
1 Liter = 2.18 lb
1 Liter = 33 oz (a typical water bottle is 24 oz)
I found it interesting that drinking a bottle and a half of water will result in a 2lb gain.