How long before 30-minute workouts on a preprogrammed treadmill will show results?

I'm a 57-year-old female, 5'7", weighing about 200 pounds. I am a member of LA Weight Loss - working diligently at eating the right foods. How many days a week, for how long, at what incline, etc., do I need to use the treadmill before I begin to see my body start taking back its shape?