The best way to check is to dose ammonia (If you can dose 2ppm that is best), and if in 24 hrs , ammonia and nitrite are 0 you can slowly start adding fish, and during the week to test the water. If you’re cycling with fish food, it is hard to know how fast it is rotting/ammonia being produced, and so if you headed that route I would suggest no more than a couple fish, depending on the fish and tank size.
Before you get fish, try to do some water changes to get nitrates below 40, preferably under 20.
You’ll have fish in there in no time, don’t worry.
Itís more keeping aquarium water than actually keeping fish