Hi @Benedikt Kaiser,

How are you getting on? Did you see my response below?

The 'Metric Definition' feature of ServiceNow allows you to track the timestamp of any record. Commonly known as 'Metrics', they can also be used (and are more commonly used) to track duration periods such as the time between certain states, for example, New to Assigned.

Find the link below where Armit has provided a tutorial if you're not familiar with Metrics.

To help others (or for me to help you more directly), please mark this response correct by clicking on Accept as Solution and/or Helpful.

Thanks, Robbie

https://www.servicenow.com/community/developer-articles/servicenow-introduction-to-metric-instance-s...