A few tips about fish less cycling. Don't forget you need a source of bacteria, be it a filter from an old aquarium (or media), biological supplement, or I've heard people have just used plants from cycled Aquariums.
I water changed (40%) every 4 days, the JBL substrate I used told me to, but also it helps reduce extremely high readings of ammonia or nitrite.
Make sure you know how much water is in your aquarium. Loads of quotes regarding tank size are outside dimension sizes. My "70 Litre" tank actually only has 55 litres of water in it!.