If you don't have any fish at present then there is no need to add the medications, all aquariums contain small background populations of bacteria and they only become a problem when they infect a host (the fish) and multiply themselves. Stress from poor water quality is the main constituent for disease.

Strip test kits do tend to be somewhat unreliable, a liquid master test kit is what you need and I would highly recommend buying one for ammonia. During the nitrogen cycle ammonia is broken down into nitrite and then nitrate, phosphate and nitrogen gas. The last three are generally harmless except in very high concentrations.

Have you added any chemicals (i.e ammonia) to kickstart the cycling process? Until you do then there will be very little in the way of detectable ammonia and nitrite. Also during the cycle there isn't any need for water changes, the only time that I would recommend carrying out a water change is at the end of the cycle, to remove most of the accumulated nitrate.