Audit profile retention time and pruning

I am seeking information on the pruning of the audit log and how it works.

I want to remove some entries from the log, and am considering if it is safest to let ignition gateway do the work by temporarily setting the pruning on after 5 days - but if I configure that, will it happen right a way, or will it happen at a certain time of day? My alternative is to execute a query to remove the rows, I prefer letting ignition do the CRUDs

The prune task is run every 30 minutes, counting from approximately whatever arbitrary time the gateway started up. You should see a datasource audit profile prune scheduled task on the Diagnostics -> Execution page on the gateway.