Problem

Currently, there is no smart value or direct method to retrieve the approval creation time, as this information is not automatically captured in a dedicated field.

Suggested Solution

Have a approval timestamp something similar to Work item created date and time.

Workaround

We can work around this by getting the time the work item entered the associated approval status by using JQL or automation rules to capture the approval timestamp and store it in a custom field, such as a "Date Time Picker" field.