Your tank goes through a 4 to 6 week cycle if you are starting from scratch. It goes through 4 phases; a serile enviorment, then your ammonia will spike and come down (this is caused by the fish defecating and uneaten food decaying / the living bacteria you are growing in your filter/rocks/gravelbed are the cause of the cycle) , then your nitrite will spike and come down (for the same reason as above the bacteria are eating these and converting them), after the last phase you are left with nitrate.
You then control the nitrate with carbon, water changes, live rock, and plants or algea.
If you are doing water changes during this cycle all you are doing is prolonging your tanks cycle time and possibly causing undo stress to your fish. There is no need to do a water change to your tank while it is cycling.
I hope this information helps you out.