When is data pruning triggered?

I enabled data pruning and set the Prune Age to 1 Month and saved the changes. Partitioning is enabled with a Partition length of 1 Month.

At first the data (table partition) was not pruned, but eventually it was. I believe it was after at least 15 minutes or so after enabling pruninig. I did not record the time when I enabled pruning.

This is acceptable behavior, but it still left me wondering what triggers the pruning so that I can know when to expect the data to be deleted? Is it configurable in anyway when the pruning would occur?

Thank you,
Bob

:scratch: when the history pruning is triggered ?