Let's say you have orders for 20TH and 10TH arrives with the first hardware delivery.
Instead of an even split, could you fill the orders proportional to the hashing power that was purchased? In other words, I purchase 1TH (5% of this example). That means I would get 500GH up and running with the first shipment. That seems more equitable than an even split in regards to the people who purchased large orders.
Should be an interesting week!