Capture the starting point
Suppose a team wants to reduce the time needed to approve a purchase request. Define when the clock starts and stops, which requests are included and how exceptions are treated. Sample the process before the change. Otherwise, a later result becomes difficult to compare with anything more reliable than memory.
Count the costs that remain
Include setup, integration, data preparation and training as well as recurring operation and support. Time saved is not automatically cash saved; explain how the organisation expects to use that capacity. Keep assumptions visible so a reviewer can change them without rebuilding the entire calculation.
Check the result with the process owner
Compare a similar mix of requests over a stated period after adoption. Ask whether staff introduced workarounds or moved work to another team. Pair the timing measure with an error or rework check. The most useful result explains both the improvement and the conditions under which it was observed.