It is very much important to match the books of account for each parties dealing with the financial transaction. Even in some countries it is compulsory to deliver the order with delivery challan and invoice for the order they going to deliver.
In many cases it is difficult to deliver whole order at once, so many times they have to prepare deliver challan and invoice based on the partial delivery.
Confirm sales and deliver in 2 different deliveries as below.
Create a invoice at the time of delivery and then confirm the invoices.
Lets do the payment at once for two invoices we have prepared based on the delivery.
Please go through the full story to understand invoice based on the delivery orders and payment at once.