How to set the due dates of performance document task based on the document creation date

Summary:

How to set the due dates (Standard Alert/Critical Alert) of performance document task based on the document creation date. In performance template, we have provision to have a specific date, but the requirement is like, if we create a performance document today (30-Sep-2024), it should be due by next 20 days, and the standard alert should get triggered on next 15 days onwards.