Hi Kate, You have to drink 200-300 mls of liquid. They will have a water bottle there for you to have and you drink just a medicine cupful at first. Depending on how everything goes, you need to be up walking, drinking, comfortable, with vital signs(b/p, oxygen, heart rate) stable. My first fill was 6 weeks after surgery. The last time I went there they said they may start moving it to 4-5 weeks after surgery because the last week you start to feel really hungry. I go for a dietary appointment today and for I hope another fill, cause I'm to the point where I could chew my arm off . Both nurses that I met at the Bariatric center were nice. The receptionist can be very moody though.- Sheila