An old legend tells of an Ethiopian goatherd discovering coffee when he noticed his goats consuming the beans. While the story may be a legend, coffee's origins do seem to go back to Africa before moving to Arabia and eventually the rest of the word. Personal taste will dictate what you regard as the perfect cup of coffee, but there are a few basic principals that can help you know when your coffee is ready to be served.
Read the package. Your coffee should tell you at what temperature and for how long you should brew your coffee before serving.
Listen for the tone. Most drip coffeemakers have built-in alarms that will signal when your coffee is finished percolating and ready to be served. Try to serve it shortly after you hear the tone.
Set a timer. If you decide to make coffee using an alternate method, such as a stove-top percolator, you may have difficulty knowing when your coffee is ready. Set your timer for approximately 7 1/2 minutes at a temperature of 205 degrees. If you see coffee splash onto the glass dome at the top, remove the percolator immediately
Taste it. Your personal taste is the best measure of when coffee is finished. If the coffee tastes good and has a suitable temperature, it should be ready for serving.
Serve it quickly. Avoid letting the coffee sit for more than 15 minutes. Your coffee will begin to lose taste shortly after it's done brewing. The longer it sits, the worse it will taste.