Changing your bill due date is not currently available. However, you can easily request a due date extension by logging into Your Account and then select the Payment Options section and Set Up Payment Arrangement. With this option, you can select a due date anytime in the coming month.
If you prefer your bill to automatically pay on a pre-selected date, your bank may have options through their auto-payment program that may help you ensure payments are made when it is more convenient for you.