Unfortunately, we have no information on arrival time for specific products. It is not advisable to add out-of-stock goods to package, and because it may take several months for them to arrive. Not unlikely, out-of-stock goods will be excluded from sale. You can place separate orders. One specifies only available items, and the other one specifies out-of-stock items.
In order to automatically reserve a currently out-of-stock item upon its arrival, you should place an order and pay for it.