How often should I do my 10 Minute Solution dvd and how long until I see results?

Okay so I'm 18, 5'5 and 140 lbs. I'd like my midsection to be a but smaller and more toned so I purchased the 10 Minute Solutions: Blast Off Belly Fat. I was wondering how often I should do these workouts (I usually do 2-4 at a time) and when I will start seeing results. I also do cardio work (running on a treadmill since it's still chilly where I live three times a week). Any help is much appreciated!