The amount of clotting and when it falls off varies from person to person. For the most part you really just want to leave it alone until 6 weeks or so, I didn't pull back on anything until about 8 weeks, just let things heal away. It's nothing to be scared or worried about. This is major surgery, and healing times are long, so don't get concerned if things take time. The best thing you can do is just relax and heal. The only things you have to worry about are any of the things your surgeon tells you to call on if they develop, usually bleeding, fever, etc, but these are rare. You'll be fine!
Be careful about losing any more weight before surgery, you certainly don't want to try and lose 10 pounds in 20 days, you will lose weight in the hospital. Many doctors discourage against weight loss with two weeks or so before a surgery and six weeks or so afterwards.