When you restrict your project to run against a specific label and all the nodes in that label are setup to go online/offline on demand, the polling log contains the following when all nodes are offline:

Perforce Software Polling Log

Started on Sep 5, 2014 2:49:00 AM
We need to schedule a new build to get a workspace, but deferring 1,229,335ms in the hope that one will become available soon (all_suitable_nodes_are_offline)
Done. Took 0.17 sec
No changes

I'm guessing this meaning that the polling was not done. Right?