Deliver first, bill later

This is one of the two routes through the middle of a sale: the goods go out first, and you invoice afterwards. It suits shipping in stages and billing monthly, because several deliveries can be put onto one invoice.

What happens to your stock

Sending goods and billing for them are two separate events here, and the system treats them that way.

Confirming a delivery takes the goods out of the outlet they left and holds them as goods on their way. They are no longer available to sell, but they are not yet a cost either.
Marking the delivery as delivered is the point the goods become a cost of sale, dated on the day they actually arrived.
Invoicing records what the customer owes.

The in-between state is the useful part. It answers "where is that stock?" honestly for goods that have left your shelf but not yet reached the customer — which a single-step system cannot do.

Deliver the goods

Open the confirmed sales order and click Generate Delivery Order.
Check the quantities. Reduce a line if you are only sending part of it — the rest stays available on the order.
For goods you track by batch or serial number, choose which ones on that line. You can let the system pick oldest-first, or choose specific ones.
Confirm. The delivery is created and the goods leave your outlet.
Print it with Print to send with the driver.
When the customer confirms receipt, open the delivery and click Mark as Delivered, setting the date they actually got it.

The delivery now shows Delivered.

Invoice one or several deliveries

Open a confirmed or delivered delivery note.
Click Generate Invoice.
Look at the window carefully — it lists this delivery and every other one still waiting to be invoiced for the same customer and currency.
Tick the ones this invoice should cover.
Check the quantities and confirm. One invoice is created covering all of them.

This is the step that makes the route worth using: a customer who took eight deliveries in a month gets one invoice, and each delivery is still individually traceable on it.

The invoice is created already confirmed. Check the ticked deliveries and the quantities before committing — undoing it means deleting the invoice, which is refused once a payment has been matched to it.

Worth knowing

You can invoice before the goods arrive. A confirmed delivery is enough; it does not have to be marked delivered first. But mark it delivered when it lands, or your cost of sale sits in the wrong month.
Once you deliver against an order, that order is committed to this route. The bill-first buttons stop being offered on it. See From quotation to money in the bank.
To reverse a delivery, the action depends on whether it has arrived. See Taking goods back and crediting a customer.
Check what is still uninvoiced on the order itself, or in Linked Documents on any document in the chain.

What can stop you

If Generate Delivery Order is missing, the order is still a draft, or everything on it has already been delivered, or it has been closed.
If a line will not let you deliver the quantity you want, there is not enough on hand at that outlet. Check the stock balance first.
If Generate Invoice is missing on the delivery, it has all been invoiced already.
If another delivery you expected is not listed in the invoice window, it is for a different currency, or it has already been invoiced.
If you cannot delete a delivery, it has been invoiced. Remove the invoice first — and see Why can't I edit or delete this? for the rest.