question

Process Flow is probably the most straightforward way like Sam mentions. But you can also do it another way using delayed messages and closing the input ports of the Queues if that is preferred. In the attached model (test10000.fsm), you'll see how to do this in the Queues' OnEntry, OnExit, and OnMessage triggers.

In the OnEntry trigger, along with the Set Object Color logic that was already there, I added the Close and Open Ports picklist option to close the input ports of the Queue when it has reached capacity. This is done by checking to see when the contents of the Queue match its Maximum Content value. Since the Queues are doing batching and are using the "Flush contents between batches" option, closing the input ports at this time is redundant, but this way can still be used when batching and flushing aren't being used. Regardless, the input ports still need to be closed before the last item leaves the Queue and this works just as well as doing it at that time in the OnExit trigger.

Then, in the OnExit trigger, I send a delayed message when the last item is leaving the Queue. This is done by checking to see when the content of the Queue is 1, indicating it is the last item in the Queue that is leaving the Queue. The delay time is 52.4 as indicated in your requirements.

Finally, in the OnMessage trigger, I use the Close and Open Ports option again to open the Queue's input ports. I didn't worry about setting a condition since the only time the Queue will receive a message is 52.4 seconds after the last item leaves the Queue.