Set up an approval task with one current proof, a decision question, and a due date.
Show the current visual proof behind the reviewer's decision.
Your reviewers get a clear task for the current proof. They know what decision to make and when it is due.
Assign creative proof signoffs from meetings to reviewers.
Your reviewers get a clear task for the proof decision, with the link and due date from the meeting action item.
Put each submitted design proof on the reviewer's approval list.
Your reviewers get a clear approval task on the submitted proof, with the decision to make and the date you requested.