When do you beginning counting your calorie burn

Weaz66

I don't have a HRM yet. So I rely on MFP and other websites to give me a calorie burned count. I began doing some low-impact aerobics on dvds. My question is: Do I start counting the time limit after the warm-up (when my heart rate will begin to get higher)? Or do I start it to include the warm up? The same question applies to ending the routine: Do I stop the time when the cool -down begins? Or after the cool-down? Curious to see how others document it!