What is the time between gold coins appearing on island?

The Estate produces 1 coin every 10 minutes, reaching max of 60 after 10 hours. That means 7.5 hours to get 45 coins, minimum of 16.7 hours to get 100, minimum of 36.7 hours to get 220. All other buildings produce 1 coin every 40 minutes, reaching max of 15 after 10 hours, but the sign above the building will not appear until 5 coins are ready to harvest.