There are 2 types of Pre-order:
1) New Game Pre-order
2) The product was out of stock but opened for pre-order.
For new game pre-order, it is generally delivered between 1 day to 1 week time, solely depending on the decision of the game publisher.
As for out of stock products, this will take up from 24 hours time to 2 weeks time, depending on the availability of supplies in the market.