There is no set amount of time that it takes for a tank to cycle. One of the most important things you can buy in this hobby is a good test kit. When starting a tank you should keep an eye on the ammonia, nitrate, and nitrite levels. And, one of the most important things you can do before and after getting into this hobby is read books on the subject. If you read a book on general saltwater tank/reef keeping it will explain the cycling of wastes and chemicals in a tank. This of course should have been done before starting the tank, but your situation is very common.