Please forgive my ignorance.

Does the code for this plugin just go in a template?  Any template?

Yes - any template ... but it should be one that is frequently called/visited. The cron functionality isn’t truly cron but depends on the access of the template: no access, no DB backup.

Thanks for your answer - I’m glad I asked (I was afraid it was a stupid question, if there is such a thing) I was going to put it in it’s own template which woudn’t have been accessed at all.