Notification - If cell is blank

So I'm wanting to set-up a notification to go out to the contact anytime the "Completed By" column in that row is blank. Would like a daily notification sent out until that cell has a value. When setting up the automation, it looks like a change of some type has to occur in the row in order for the trigger. Maybe I'm in the wrong section but how can I setup a notification for this scenario?

Best Answer