Please please PLEASE do a fishless cycle as ibble and stang have already mentioned.
It's SO much easier to do and you don't have to worry about killing or harming any fish in the process.
Danios are hardy, but that doesn't mean the cycling process isn't going to harm them.
When we first got our 28gal.. we let impatients get the better of us and we got some danios. They were great fish but unfortunatly, the cycling process ended up killing all of them. It's aweful to see such a lively group of fish get red gils from the ammonia and nitrite in the water, and then seeing them laying around not chasing eachother and eventually losing color and dying.
Anywho...I enjoy danios. Now I've head alot of people say they're nippy, but the ones we used to have never nipped. They chased a whole lot, but they never nipped eachother or the other fish (which included male guppies). Now that's not to say that ones that you got wouldn't nip a betta though. Unfortunatly, male bettas' long fins make tasty treats for other fish.