How soon will I be able to walk after I have bariatric surgery?

Very soon. You should be up and able to walk later that day after full recovery from anesthesia.
Several hours. Most patients are able to (and should) get out of bed and walk within a matter of hours after laparoscopic bariatric surgery. This will help reduce the risk of blood clots as well as stimulating deep breathing, which will help reduce the risk of pneumonia. After going home walking or some other aerobic activity should be a daily activity.
Hours. . It is important to get up and walk to prevent lung problems and leg clots. Typically a urine catheter is not placed, ensuring at least the need to get to the bathroom.