First of all the delivery time can be diferent one if you do use a diferent way of paying your order.

Additionally the AC Shop software will say on stock as long as there is at leat one item of this component available in the shelfs - the software does have no clue whether or not this item has been sold already. It is physicly present - it is on stock.

If you like have one guy you can talk to try Stefan Krumme - Aqua-computer-berlin(.de) he i usally responding to e-mails and will tell you about delivering times on the telephone.

It would help a bit to know what you actually ordered.
But since you do say it was a big order, there is a good (or for you bad) chance that at least one of the items is not really on stock.