Hi Ash, generally a cycle takes about six weeks. What did you start the cycle with a week ago? Pure ammonia? Sounds like you filled the tank a week ago, added nothing to the tank until you added food which cause the ammonia to register on your test. If true the your cycle started when you added food to the tank. Many here use pure ammonia (from the hardware store and without surfactants) to start the cycle. It is a lot cleaner then adding food plus you can control the amount of ammonia added to the tank. This will give you an idea http://www.fishlore.com/aquariumfish...s-cycle.19627/.
Pat