The Average first response time report shows you the average response time for the selected period. This time corresponds to the time between the first client message and the first agent response of the conversation. The response times are calculated with respect to when the customer message is received and when the agent replies — not when the agent reads the message for the first time and the time they reply to it.
On chat channels, the average response time corresponds to the average customer wait time to chat with an agent.
If the average response time is far from your target, possible causes are the team is understaffed, agents have replied to old messages, or agents have replied to a new message from a thread whose old messages had been archived. For the third cause, It is always the time elapsed between the first customer message of the thread and the first agent reply that is taken into account.
If the average first response time differs significantly when switching to business hours, you may want to consider extending your opening hours so as to decrease the average response time.