Hi sideshow - BigIan has given you the right info for normal running of the tank after it is cycled, but for you right now, nitrate(NO3) is not particularly important.
You are in a Fish-In cycling situation unfortunately (I think, unless there was mature media from another tank and we didn't know) as by definition the fishless cycling will not have really proceeded beyond the first of 3 phases in only two weeks. Its possible though that if the fish load is not too heavy for the tank volume that the water changing of the fish-in cycling will not be too heavy.
The next thing to do is to see if it keeps coming up to 0.25ppm ammonia within a day after your water change for that day. Also check your tap water ammonia level to be sure additional ammonia is not coming in with the water change.
~~waterdrop~~