Personally I think that store bought bacteria stuff is a waste of hard earned money.
Most would agree that in a brand new tank - nitrifying bacteria will only grow in response to an increase in ammonia - period. They grow logarithmically - first 1 splits into 2 - those 2 into 4 - then 4 into 8 ...... etc.
Eventually you have a population of bacteria that is expanding in a balanced fashion in relation to ammonia load of the tank. In the initial cycling of a new tank - either with damsels, raw shrimp, live rock or whatever ammonia source you choose - these first bacteria will conver the ammonia to nitrite, until the next type of bacteria will start to grow and convert the nitrite to nitrate. The whole process begins over again - growing at a rate proportional to the amount of ammonia and nitrite that is available.
The initial "cycling" of a new tank should not be confused with the ongoing nitrogen cycle that is always present in an established tank. Each time a fish excretes - everytime an animal or plant dies in the tank, or any organic waste begins to break down - ammonia fuels the nitrogen cycle once again. There is a true beginning to the "cycling" of a tank, but there is no real beginning of the nitrogen cycle in general terms. It's a natural, continuous circle.
Sorry back to your question. You could dump all the bacteria you want to in a new tank - it may indeed allow you to initially cycle the tank faster - but if speed is what you are looking for - then you may find this hobby very difficult to adjust to.
Of course all of this is just my opinion, and really doesn't amount to a hill of beans
Save your money - go the time proven natural way - test your water often and watch as it all happens
p.s. Trying to prevent a large re-cycle of an existing tank by making a drastic change to the balanced system is a whole other story.