OohFeeshy
It's only forever; not long at all...
I agree with Miss Wiggle, the tank isn't big enough for danios (or at least that species). If you want danios (they're all active), there are a few much smaller species that are also much prettier than zebras/leopards. Or if you want tetras, it might be a good plan to opt for a hardier species (such as black widows) and swap your two danios for three tetras. That should be a similar bioload while not being too few tetras. Once ammonia is at 0, I would add the betta (if you still want a betta), then a few weeks later, the rest of the tetras.