Configuration is in admin menu System > Configuration > Sales > Payment Methods > Walkin. This is a setting for creating a shipment while the order is being created, the order status can also be specified. This extension is all useable from the admin.
You can set the option, "Creation of Shipment" to Yes or No. If you were accepting payment and immediately handing the item to the customer, you would want to enable this option to "Yes" because the delivery is complete. If you were accepting payment, but you needed the item to be made first, you would set this option to "No" because the delivery won't be complete under after manufacturing. While the item is being made, you can set the New Order Status. For example, if the item is being made, you could set the Status to "Processing" or "Pending".