It seems that infinite pre-orders are being accepted and until Friday you will receive a confirmation email whether you belong to the first launch wave. After that, delivery will simply continue in waves and order. It's actually quite a normal procedure.

At the moment we are still accepting pre-orders. As Fish Scale says, there will be further allocations after release and it will be delivered after orders are received. We don't know the further allocations yet.
Edit: we are no longer accepting pre-orders.