Hello Kevin
I understand the guy in the shop, and the makers of the starter bacteria, will tell you that after putting the product in the tank "everything will be good for putting fish etc in the tank". This is generally not true and i'm sure they will be happy to sell you more products/fish to fix the problems that come up.
An aquarium is basically a self contained eco system for an aquatic environment and it will take months for all the natural bacteria etc to balance out in that system. Generally we just worry about the toxins that are present, Nitrates etc, and once they have stabilized somewhat we will add fish. This is just part of the ecosystem balance and there is a lot more going on before a balance is reached. Shrimp are very sensitive to their water parameters and therefore need a mature tank, that has completely stabilized, to live a happy life. Also every tank is different, as they are all a self contained ecosystem, so this balance will take a different time, and do different things, for each tank.
I would suggest to you that you did a lot of reading on fishless aquarium cycling and then get the tank in a mature state before adding some more shrimp. Or, and i dont really agree with this, get 1 or 2 guppies and put them in for a couple of months to mature the tank and filter. What ever way you decide to go just remember that there is no real quick fixes for getting a tank mature and in balance. Nature does not make a stream and have it mature in just a week or two does it?
Have a look through some of the aquarium set up threads on this site and take note of the start dates of the threads. Then look at the dates when they start to show pictures of their shrimp in the tanks. Most will have let the tanks run for months before adding shrimp or have moved a mature filter from a tank that has been running for years.
There is a lot to learn about keeping shrimp so keep reading and learning and good luck with your setup.