While the workflow will vary by project, the key milestones in your internal process will remain fixed. 

Determine names for each of these major milestones, including where the change may fall out of the workflow process and why. Examples include:

• Identified: Initially set up in your tracking system
• Proposed: Sent to the customer
• Approved: In some form from the customer giving you the OK to proceed
• Executed: Fully executed contract change order or fully billed and paid

You may choose other stages in between for more granularity, depending on your workflow and the dynamics of your projects. At the end of the change funnel, you can track billed and payment dates.  

There are also other status codes where the change falls out of the customer change funnel:

• Budget Revision: Internal - turned out to be a scope gap or value engineering not submitted
• Voided: They decided to not go forward with the change before any costs were spent
• Settled: Agreed on some sort of trade after you had spent some costs
• Dispute: Agree to disagree and work on settlement per the contract terms

Setting up clear status codes and using them consistently allows more effective management of changes.