It ALSO depends on making sure you have NO BYPASS.....
What kind of filters do you have it in? Eventually assuming it's placed well with no bypass, it will start working it just may take a few days, assuming you're not having a bacterial "bloom" of sorts.
One last thing....learn patience or you will not do well with this hobby. We are essentially keeping very tiny tiny pieces of nature in out homes, and nature can never be "rushed" but so much, or you will eventually lose on a bigger scale (by using chemicals, changing water parameters too fast, etc.)
Best of luck....