I want to schedule a custom HCM Payroll Extract for every 15 days. What is the best approach?

I want to schedule my custom HCM Payroll Extract to run after the Payroll Run is completed which runs for every 15 days. What the best approach to achieve this? Is it better to create Fast Formula for scheduling frequency at extract level or to create Payroll Flow. Please attach the sample steps for the same.

Thank you.