Welcome to AC. :welcome:This is a great place to learn all about fishkeeping.
Don't add any more fish. Danios are hardy, but really the majority of experienced fishkeepers here prefer to do a fishless cycle. It is actually faster than with fish, because now you have absolutely got to keep the ammonia as close to 0 as possible and then the nitrites as close to 0 as possible or your fish will suffer.
You have to do this by diligent monitoring of the parameters and responding immediately by doing water changes with dechlorinated, temperature matched water. You will need to keep the detritus to a minimum by vacuuming the substrate periodically.
Ammonia burns their gills and skin, and nitrites prevent the uptake of oxygen in the gills. Being subected to the swings of those harmful byproducts in your tank can wreak havoc with the immune system of the fish, leaving them susceptible to disease and/or parasites, and can make them suffer.
You will need to do water changes everytime you find ammonia and then nitrites in the tank. Certainly .25 or less and really water changes should be done anytime you find any detecable levels of ammonia or then nitrites.
If you can get Prime by Seachem this will really help protect your fish during the cycle process. Prime not only removes chlorine and chloramines, but it detoxifies ammonia and nitrites for appx 24 hours in the tank.
That can come in handy when you find detectable levels of ammonia and/or nitrites. You can follow the directions on the bottle and dose the tank to detoxify the ammonia and nitrites, giving you some time to do the water changes.
Hang in there and stay on top of things and always feel free to ask questions here on AC. Never think any question is dumb, (I am speaking from experience in asking many questions I thought were dumb, but no one ever treated me that way) and follow the advice of these guys.
Don't listen to the pet store people, no offense intended, but they want to sell you things and a lot of times those folks don't really have accurate knowledge.
The folks here keep fish and have been keeping fish for years and years. They know their stuff and really want to help. They have been through everything the beginning fishkeeper experiences, all the mishaps and mistakes. ( I speak from experience here, too, lol.)
Again, welcome to AC.:thm: