The plants need to get much bigger. When they do you can start to add fish. However, there is a really easy way to know where you stand in this respect.
Once the plants have grown in a bunch, do a test. Add 2 ppm of ammonia to the tank, test it in 12 hours. If there is 0 Ammonia you can add a bunch of fish, but not quite a full load to leave some wiggle room. If the the ammonia is not 0 in 12 hours test again at the 24 hour mark. If it is 0 then, add fish, but make it a bit lower load- something about 50-65% or so.
If the tank fails to clear all the ammonia in 24 hours, then you have two choices. You can continue to dose ammonia according to the directions for fishless cycling and wait for the process to complete. You should reduce by 1 day the intervals between testing though since the plants will accelerate things.
The other choice is to add a few fish and proceed as if it is a fish in cycle. The plants should prevent any real build up of ammonia or nitrite because the ammonia load will be low and the plants will handle most of it. You may even never read ammonia or nitrite. But you should still add gradually to be sure. And never add any more fish if you have either an ammonia or a nitrite reading.
