Free month subscription

I created a battle.net account and signed up for a 6-month recurring subscription. Will this subscription be charged on my credit card after the first month (free) or right away? I want to cancel the subscription before it gets charged on my card, and I figured I could do that because the first month is free, which should mean they should only begin charging after that month.

Also, if I were to cancel my subscription before my free month runs out, and then resubscribe later, would be free month be gone or would I have (30 - days I have played) free days left?