Respond within a day or two. Speed matters most on negative reviews, where the visible gap between complaint and response IS the message. Review responses are read by the next hundred prospects, and platforms treat response rate and recency as engagement signals.
'How many do I need' has a competitive answer, not an absolute one: search your service, count the top three profiles' reviews, and that neighborhood is your target. Passing the competitor ahead of you matters more than any global number; velocity (steady weekly arrivals) matters more than the total.
Both metrics trace to one habit: the ask built into job completion, every job. Count is an asking metric. The system in our review guide.