The actual nitrifying bacteria are a bit too delicate to be supplied that way.
Here is what I would do:
Set up the tank and add ammonia until the test reads 5 ppm. Then see how long it takes for the bacteria to remove it. Monitor the nitrite and nitrate, too.
Maybe the product has the old bacteria that people used to think were the nitrifying bacteria. Studies have shown that these bacteria do not live long in the tank.
Maybe the product has other bacteria that are helpful, perhaps decomposers that will help by composting the waste (fallen leaves, fish poop). Those sorts of bacteria do enter a dormant phase and are much more easily shipped.
I sure doubt there are Nitrospiros species in there.
Anyway... after you have added that initial dose of ammonia, keep on adding it as needed to keep it at 3 ppm. If you have not already read about the fishless cycle, do so.
Yes, as pejerrey suggests, lots of plants can provide a lot of bacteria (nitrifying and other species) and the plants themselves are part of the nitrogen cycle. You can indeed set up the whole tank, fully planted, and add fish right away. (a reasonable load, anyway). The 'fully planted' part means there are enough plants to pretty much hide the back of the tank.
