Jump rope can be utilized as a HIIT workout. I incorporated jump rope in my warm up for my leg training days and got a good pump in the calves, elevated heart rate, and this contributed to me getting to 8.9% BF last year. Three times a week is plenty make sure you are taking short rest periods between sets to maximize efficiency. Since you are using it as a warm up make sure you find your sweet spot for intensity, get the heart elevated and the sweat dripping but don't burn yourself out before your workout. I recommend 15 minutes at maximum for a warmup but you will find what works for you. I think it's a good idea and let me know how it works.