This asset will allow you to schedule events using a cron based approach.
It contains an adaptaion of the cron implementation by rcravens that can be found, along with an in depth explanation of the cron in Random Sparks website. If you want more information about the cron syntax you can visit the wikpedia page for cron
[I will try to resolve any doubt in the unity's forum post for this plugin]
As you can see on the screenshots the Component includes a custom editor with shortcuts for most common used triggers. And a quick help guide.
More Info: _https://assetstore.unity.com/packages/tools/cron-scheduler-39464