When a customer pre-orders a product with pre-order purchase options attached (currently charge-upfront, charge-later and deposit-upfront pre-orders) The resulting Shopify order will have an ‘on hold’ fulfilment status. This means the pre-order line item(s) will be ignored by ERP/shipping/fulfilment services. 

If the customer has a mixed order of some pre-order line items and some buy now line items, the former will be set to “on hold” and the latter set to “unfulfilled”.

Then once you’re ready to collect payment, you can trigger the deferred charge or “release fulfilment” process. If the payment is successful, the fulfilment status of the order will change to ‘unfulfilled’ in the Shopify admin so that it can be fulfilled.