Oh dear!
What sized of tank do you have?
And what fish species are you expecting?
The more information you can give, the better, is there already plants in the tank, what size, what water hardness you have (this is essential as depending on the pH, gH and kH levels, these can affect the cycling).
Hmm, do you have another tank thats set up and running or perhaps any friends or relatives who has a established fish tank?
If so, then you would have a couple of options right there.
Am a little annoyed the LFS won't hold the fish for you for a while but have to say am not that surprised.
But if LFS won't hold them and you have no access to any other tanks then your choices are limited am afraid.
First choice is to let the fish go, give them back to the LFS and you might get store credit for them. Then you could do a Fishless Cycle.
Cycling Your First Fresh water Tank
Second choice, doing a Fish in Cycle, this is not a recommended option that we usually give but sometimes needs must. Here are a couple of article about fish in cycles, I'd urge you to read them carefully so you will have an idea for what you would be expecting if you decide to go down that route. Lots of water changes daily and water testing.
Rescuing A Fish In Cycle Gone Wild - Part I
Rescuing A Fish In Cycle Gone Wild - Part II
Zero nitrite and zero nitrate is what you would expect of an uncycled tank. Even so, 8ppm of ammonia is far too high, even for doing a Fishless Cycle. I would do a 75% water change to try and get that level down if you are planning on a Fishless Cycle, if doing a Fish in Cycle then a 100% water change would be needed, you cannot have any ammonia in the tank for new fish in a new tank.
First thing I would do is to get a bottle of Tetra Safe Start or Dr Tim's One and Only Nitrfying Bacteria, if you can, some filter media from a established tank, all these will help seed the tankwith the relevant bacterias you need for dealing with ammonia and nitrite.
Second, get lots of fast growing plants such as floating plants, elodea and vallisernias, that sort of thing, these are good with helping to take out ammonia and nitrates fromt he water column.
Thats all I would suggest for now until we know what your plans are regarding the new fish.
And most of all do not PANIC, we are here to help with advice and suggestions as best as we can.