AQ message propagation schedule

Hi,

I am using Oracle 9i AQ. What configuration i need to achieve this:
Suppose there are 3 messages in queue.

1) Dequeue 1st message.
2) wait 30 seconds
3) Dequeue 2nd message.
4) wait 30 seconds
5) dequeue 3rd message.

there is the 30 seconds that i want to implement. How do i configure the queue to have this effect?

I have try to configure latency to 30 seconds, the result is:

1) wait 30 seconds
2) dequeue 1st, 2nd and 3rd message.

Which is the undesirable result.


Thanks in advance.