Regardless of how everyone does it, you have the tank set up, and you have the fish in it, so you're in the middle of a fish-in cycle whether you want it or not lol.
So keep an eye on the ammonia and nitrites, do regular water changes when you notice either going up, and in a few weeks you should be down to 0 for ammonia and nitrite, and the nitrates should be controlled by your water changes from that point.
Depending on how hardy the fish you got are, the ammonia spikes can be a little higher if your fish are hardy, but if you have anything delicate, I would keep the levels to a minimum and change water often.