you need fish or some hardy animal to add waste in the tank. The buildup of waste is what starts the cycling process. There needs to be nutrients in the water for the bacteria to eat and produce and multiply. The bacteria is what breaks down the amonia. When there is enough bacteria to break down all the amonia when the test says 0 that is when your tank is cycled. When you amoina is in check then you do a partial water change and slowly add more fish.
A couple of points of correction/addition since this is very important subject.
First you need ammonia, this does not necessarily have to be produced by a fish or animal. it can come from a bottle of clear ammonia just as easily.
Secondly, ammonia is the first half of the process, nitrites are the second. when your ammonia test reads 0 nitrites will still be quite high, and can be harmful/ fatal to your fish. Ammonia and Nitrite must both be zero with nitrates present (proof of ammonia and nitrite consumption) for the cycle to be complete.
Read the cycle sticky in the newbie forum, also run a search on fishless cycling. There are many ways to cycle, including fishless and fishy,but, Fishless cycling is the easiest and prepares a tank for a large bio-load the fastest. Fishy cycling requres the most dilligence, the most work, and has the highest risk for damage to your fish.
In answer to your fist question, it's possible but highly unlikely that your cycle has started. most likely some nitrates in your tap water.
HTH
Dave
