How do you measure RMA turnaround time?


How do you currently measure your turnaround time for repairs or calibration? Here are some different options I have heard about:

1- Clock starts when: you receive the product, customer first reports the issue, other

2- Clock stops when: you ship the product back, customer received the product, other

3- Clock pauses when: we are waiting for the customer, we don't pause the clock, other

Any thoughts on this?