I cycled at 3ppm, then dropped the dosing down to 1ppm until the cycle finished. I then added 12 fish in a 29g, without a spike.
Recently, I cycled at 1ppm, and dropped the dosing down to .5ppm and I added 6 fish into a 10g, also without a spike in ammonia or nitrites.
Depending on what you are adding, you will probably be able to add 6+ at a time.