However.......
If the tank has a good number of fast growing plants, you don't need to add any ammonia. Just wait until you are sure the plants are growing well and not about to die then add fish a few at a time. Taking a photo now will give something to compare the plants to to see how well they are growing.
This is a 9 gallon tank, so it won't hold many fish. And shoaling fish need to be added a whole shoal at once so adding fish slowly a few at a time may not be an option
If you would prefer to add ammonia, the plants will remove some, if not all, and they won't turn it into nitrite so the cycle will not follow it's usual course. The "add ammonia every time it drops to zero" method is not a good one as, in the absence of plants, so much nitrite is made that the cycle stalls.
I would add just 2 ppm ammonia and test next day. That will show one of three things - zero ammonia and zero nitrite in which case you'll know there are enough plants for fish; or ammonia will be lower, in which case you'll know you have to continue the cycle or grow some more plant matter; or ammonia won't have changed which means the plants have not removed any so you definitely need to do a fishless cycle.