Last updated: 2019-09-18

Source: https://support.freshservice.com/support/solutions/articles/50000000382-how-is-the-average-first-response-time-calculated-in-reports-

The average first response time is calculated based on the time taken for the very first response to be sent by an Agent to a requester.

Note: When you add a private note to a ticket since it is not visible to the requester,  it is not considered a first response.