I understand that cars are not being delivered to the dealer in any particular order. As the dealer receives notice that a car is heading their way with a certain configuration, the dealer will review its list to see if it fits a customer's order and the first customer on the list with that particular "mix" gets the call. Therefore, one's "customer number" provides, at best, some loose reference point to a window of time when he or she can likely expect a car.
Since I am #26 on my dealer's list, since my order was turned in to Lotus USA in early March, and since I probably have the only combination like mine in the first 30, I am going to gamble that my car will be in before the end of the year. Accordingly, I will start my ad campaign to sell my 911. I have arranged to borrow a friend's Explorer for the interim.
Hope springs eternal.