AWS Well-Architected Tool
User Guide

Milestones

A milestone records the current status of a workload review.

You should save a milestone after you initially complete the questions and answers portion of a workload review.

As you change your workload based on items in your improvement plan, you can save additional milestones to measure progress. A best practice is to save a milestone after major changes are made to your workload and you perform a workload review.