What brand ammonia test you got there? 0.8ppm should not be maxed out. Are you sure that's not 8.0 ppm? Like Austinsdad said, 0.8 is not normally listed on the charts - but a lot of us kind of estimate when the color is between colors on the chart. "Well... it's higher than 0.5, but lower than 1.0... but it's closer in color to 1.0, so let's call it 0.8"... that kind of thing.
In your case, the bacteria will build on the biowheel and in the sand. That's it. Granted... it's probably in the water, but not in the quantities you need to convert the ammonia to nitrates.
Don't add fish until both your ammonia AND nitrites drop to zero. Ammonia will spike first, then come down. As ammonia is coming down, nitrites will spike, then come down. Eventually they'll both be at zero, and you'll have a bunch of nitrates. Judging by your previous nitrate readings you'll have a BUNCH of nitrates! Do 50% water changes, one a day, until you get down somewhere below 10 (even lower if you want to be kind to your new fish!) and you're good to go.