Acceptance tests really need to be available in the same iteration as the story is scheduled. Think about it—you want to score the development based on getting stories done, and the only way to know if they are really done is to run the tests.
Programmers, you have the right to know what is needed. Insist on this right in the form of automated functional tests. You'll be glad you did.
Customers, you have the right to see progress in a running system, proven to work by automated tests that you specify. Insist on this right, and do your part by providing the necessary information.