If you put a sponge from an established tank into the filter in the new tank, this will instantly cycle it. You can replace the sponge in the established tank and the bacteria that's lost will repopulate the new sponge in a few hours. Then, you can add fish slowly to the new tank and test the water every day or two to make sure the bacteria in it is working.
"Fear not, my young apprentice. Just change the tank water."