How it's worked out
For one enquiry, it's the time of the first reply minus the time the enquiry arrived. For a team, take the median across a month rather than the average, because one enquiry left over a long weekend drags an average up by hours.
Two rules keep it honest. An automatic "thanks, we'll be in touch" email isn't a reply. And count business hours or clock hours, but pick one and stick to it, because an enquiry at 9pm on a Friday reads very differently either way.
Worked example, with made-up times: five enquiries this week were answered in 4 minutes, 12 minutes, 35 minutes, 3 hours and 2 days. The median is 35 minutes. The average is about 10 hours, almost all of it from the one that waited two days.
Why the first hour: in a study published in Harvard Business Review in 2011, the researchers looked at 1.25 million sales enquiries received by 42 US companies. Firms that tried to reach someone within an hour were nearly seven times as likely to have a meaningful conversation with a decision maker as firms that tried an hour later, and more than 60 times as likely as firms that waited 24 hours or more.
The same researchers sent a test enquiry to 2,241 US companies. 37% replied within an hour and 23% never replied. Among those that replied within 30 days, the average wait was 42 hours.
Where it shows up in your week
Most enquiries arrive while you're with someone else. The WhatsApp AI agent answers new enquiries on your own number, in your words, books the meeting and passes you the chat when a person should take it.