Special Items order and shipping

We have a scenario that has come up and I am looking to see if there is someway to use modifiers and other tools within EBS to accomplish this.

here's the scenario:

we have a certain group of customers that can order a exclusive product starting 1-April and it will ship anytime they want it.

the rest of the customers can order the product starting 1-Sept but can't ship till 1-Jan-13 or later.

we can identify the certain group of customers that can order the product starting 1-April.  

we're thinking to mark those customers somehow and then set up modifiers to allow them to order and ship and another modifier that makes the ship date 1-1-13 or later for everyone else somehow???