How long should I jump rope in order to lose weight?

Im trying to loose weight by jump roping, Im jump roping for about 15 minutes. 15 minutes in the morning and 15 minute in the evening. I usually do 200 jumps for 15 minutes. (50 jumps 1 minute break for stretching) How long would it take me to lose at least 30 lbs. My guess is about 3 months?