Automation rule that changes the priority based on the start date and date issue was created..

Sierra_f2eqyc

Need an automation rule that changes the priority field as we get close to a specific date for our "Start Date". 

If we are less than 7 days from the start date , change priority to Highest. And so on. 

How can I achieve this? Will I need more than an automation rule to have the issue's Start date and Created date addressed daily to then have the priority automatically changed?

Any direction is appreciated. 

 

 

 

Sierra_f2eqyc

This is my starting point, this only accomplishes what I want when the ticket is initially created though.