N.J. Stat. Ann. § 46:3C-9

9. The purchaser may cancel the contract by sending a written notice of cancellation to the seller within five business days from the date the contract is executed by the purchaser and the seller, informing the seller that the purchaser is canceling the contract. The notice of cancellation shall be sent by certified mail. If the purchaser fails to send the notice of cancellation in the time and manner provided for in this section, the purchaser shall lose the right to cancel the contract pursuant to this act and the contract shall be otherwise legally binding.