Rich, I would give your tank at least 14 days before getting worried. If you didn't seed the tank with active bacteria, it could take two weeks or more. A completed
cycle can sometimes take 45 - 60 days. Also, check your aquarium temperature the warmer the water the faster the bacteria colony can grow. Upper 80's low 90's work great.
The pet store will most likely try to sell you a bottled starter solution. I can't imagine these working well. Bacteria simple will not live long without food and oxygen. How can a pre-bottled solution that has been sitting on a shelf have active bacteria?
However, a small non-mega store, pet store might sell you some seeded gravel or a squeezing from an active filter. Both of those items will instantly put some
ammonia and
nitrite eating bacteria in your tank.