On August $3,$ Zappy Electricians LLC receives a phone call from a customer needing a repair a faulty electrical panel and schedules a consultation for a free estimate on August $7.$ On August $12,$ Zappy Electricians installs the new electrical panel. The customer pays for the service on August $16.$ According to the revenue recognition principle, on which date should Zappy Electricians record service revenue? August $12.$ August $16.$ August $3.$ August $7.$