How do I put inventory on reserve?

Hi there,
I have some products that are made to order - I have tried creating a ‘sales order’, however that does not affect the inventory in any way - and I would need to have the information available so that I don’t sell something thinking that it is in stock while it has been ‘reserved’ by another client.

Enable Delivery Notes from Customize and allocate the inventory to the customer you intend to sell them to.
the items entered in a delivery note will reduce the inventory stock.

Thank you!