You can create an unlimited number of payment schedule options in your account at Settings › Payment Schedules.  

One time payment schedules are frequently used for something like print orders, gift certificate purchases or sessions that require a payment in full at the time of booking. These are the easiest of schedules to set up. To start, you’ll choose One in the Kind option. Then, give your payment schedule a name and description for your own reference and you’re all set!  

This payment schedule creates ONE invoice that has a due date of today (the day the quote/order is booked).