Once you have created your PO, navigate to the Header tab>Other subtab > select the Disable Lead Time checkbox. This way if you place an order now, but the item will not be delivered for several months, it will not throw off the default lead time of the item and vendor for future purchases.
Next, Confirm the PO delivery to tell the system when each line item is expected to arrive so that the system will still tell you to purchase the item when backordered. From there, receive in the PO each time you get a shipment from the vendor. If a line item has been partially shipped, you can go back to the PO and adjust the delivery confirmation date for the remaining items.
