Get one of the ammonia indicator thingies for about 5 o r 6 bucks, and place it in tank. YOu will see it change from yellow to green or maybe even blue. As long as its not yellow your rock is still cycling. Once you see it start to get lighter and revert back to the yellow, then do a nitrite test so you can see where your nitrites are. Usually about a week after it reverts back to the pale yellow its good to go, but confirm with another test of ammonia, nitrite and nitrates......