I don't know about other sleeve patients, but I was also scared, but there really is nothing to worry about at this early stage.
It will not cause any issues if you are drinking.
If you eat too much/too fast you will soon know about it as it gets very uncomfortable very quickly!
Just take everyday as it comes, and don't worry about the weight it will come off when it's ready.
I couldn't weigh myself except in hospitals for a long time due to my Drs not having scales capale of weighing over 200Kg.
So I was only weighed at the times in my signature. Even then I was worried that I wasn't loosing enough compared to other people.
But it's a case of remembering that different people loose at different rates and some have a lot more to loose than others. I may have lost 50Kg so far but I know I've got almost another 100Kg to go!
Don't loose heart it will work.