Layby in manager

Im looking for a good way to do Layby. If you create invoice and let the guy just pay it off there is still process of the invoice removing the stock of manager when you create the invoice.
Is there a better way to do this in manager? If anyboday is doing this laready any advise will be appriciated.

Not knowing what type/size your inventory is, but when you create the Invoice and the inventory is reduced, remove the item to a Layby storage area.

Or, just build up the payments as Customer Credits and only create the invoice once the final payment has been received