You know, after going back and reading this thread, I never thought to ask the size of your tank. Are we talking about a 10 gallon tank?
If so, yeah, I guess it's possible you prolonged your cycle by starting water changes that early. In a nano tank, the smallest of changes can have huge effects. Most of the bacteria that break down ammonia are in the water, sand and live rock, so when you change water, you take out some of the bacteria.
There are some chemicals that neutralize ammonia, and break it down into another form of ammonia, but it still takes bacteria to eat the that. All water changes do is dilute the concentration of ammonia. All the different types of filters and types of ammonia sponges, nitrate sponges, phosphorous sponges etc, etc, that claim to reduce those chemicals do is provide another medium for the bacteria to grow in, and their real effectiveness has been questioned enough to make me think they don't work.
Also, what is your acclimation method? If you don't acclimate them correctly, that can kill a fish quickly. A little bit of ammonia doesn't kill fish, it just stresses them.
Go Cocks!!!!!