The fish food will provide your bacteria with a food source and the nitrogen cycle can be as short as a 5-6 days.
API Master Test Kits are a great resource for the new fishkeeper. They offer the ability to detect important compounds and ensure your tank is safe for fish. Before going to the fish store, preform the nitrogen based tests to ensure ammonia (NH3) and nitrite (NO2-) are undetectable. Nitrate (NO3-) should be in the range of 10-30 ppm, if it's higher, preform a waterchange to bring it down a bit. This process might take a few weeks to happen, just be patient. To speed up this process add a small pinch of fish food into your tank and follow it up with some beneficial bacteria. The fish food will provide your bacteria with a food source and the nitrogen cycle can be as short as a 5-6 days.