Your first payment won't be due until the end of next month. When you open your account, we'll set up a monthly payment of $40 (or less if the amount you owe is under $40). This will come from your linked debit card on the last day of each month and run until your purchases are paid off.
Finally, if there's nothing owing on your account, there's nothing to pay. Your account simply remains active until you're ready to make a purchase.