We ship the first available title(s) to insure members receive the maximum number of books (audiobooks) each month. New orders are generated based on the order of your queue and availability at the time the order is generated. When we receive your returns, our system automatically generates your next order by starting the top of your queue selection the first 1, 2, or 3 available books on your queue, depending on your membership plan. If the first book on your queue is currently not in stock the system will proceed to the second, third, fourth, and so on until it finds enough available books to fulfill you next order.