I will also suggest that disputing or cancelling a credit card immediately--before any acknowledgment of rescission--is not necessarily a good idea. As pointed out by
@okwiater , you're supposed to dispute transactions when they are not recognized or when the merchant refuses to issue an appropriate credit.
Disputing a valid and legal contractual charge without giving the merchant an opportunity to process a refund is not going to endear you to your credit card holder; they might not open a dispute under these circumstances.
Finally, if you intentionally cancel a credit card knowing that there is a valid and legal contractual charge (without paying), this may raise a legal issue in some states under the same type of rules that apply to check fraud etc... I'm not a lawyer, but you can't simply cancel a monetary instrument because you don't like the charge you agreed to pay.
If, however, the merchant refuses to issue an appropriate refund (per contract) after you legally exercise your right of rescission, then you may have the right to dispute the charge.......but you
MAY not have the right to refuse to pay the bill....depending on the instructions given by your credit (card) servicing company. Keep in mind: Most consumer protections (for transactions >$50) are only valid in home state or w/i 100 miles of billing address. Many state statutes (at purchase location) direct the timeline for cancellations (both rescission and refund of monies). Additionally, many a states have laws that specifically prohibit consumers from withholding payment to a creditor for lawful debts....even when those debts are under review or scheduled for refund. Again, not a lawyer.....consult one if you have legal questions.