The notification of a rate increase and of the new rate, referred to in section 91.3(f) of this Part, shall be delivered or mailed by the creditor to a customer who is primarily liable on the credit account no less than 25 and more than 60 days prior to the effective date of a rate increase; provided, however, that if the credit account provides for a monthly billing cycle, the notification may be delivered or mailed with the periodic statement for a monthly billing cycle, to become effective after the close of the next monthly billing cycle. In the case of new customers who apply for a variable rate credit account within 30 days of the time that the creditor will increase the rate on the account but where the creditor will not be able to provide the required written notification, the increase in the rate and the new rate shall be disclosed to the applicant prior to opening the account.