There is no documentation for this - no help for the plugin control in the job and no readme on the github folder. It would be great to have some simple docs on its usage, and covering things like what happens with a job not tied to slave node, or when tied to multiple nodes.
Useful documentation here (sifted from the comments):
"This plugin requires a jenkins restart (it will not work using install without restart)."
"A tickbox will appear in the trigger section of each job, tick this to trigger it when the node starts".
"When a job is tied to node labels with multiple nodes, it will be triggered when each node is started" (not sure about this - but the correct logic could be put here)