Expected payment date (or payment term) is a big part of a BtoB sales and is used in the negociation with the customer. It is supported by the Z Books invoice but the date is then not transmitted to the payment gateway. The gateway then triggers an immediate payment and do not respect the information in the original invoice.
That's a big problem for the BtoB markets!

Please add the latest payment date in the gateway interface (I know that Gocardless accepts a date in the future to trigger the payment)!!