As Ronald suggests, you can us a microflow from a scheduled event. However there are some limitation the for the content of PDFs that can be generated in a document , especially if it comes to custom styling and visualizations like the charts widgets. In that case you could consider using the Templator service from the App Store https://appstore.home.mendix.com/link/app/114043/
Scheduled events are supported by Mendix. So create a microflow that checks the setting of the user and when it is in the timeframe of the user generate the report and mail it.
Just start building and if there are running into problems edit your question with the info where you get stuck.