Fishless Cycle Between Stocking

[Iron Man]

I have a 55 gallon tank with 10 livebearers (2 swords, 5 mollies, 3 guppies) and various snails and shrimp. I want to keep the shrimp and snails but go ahead and take out the livebearers, as it is going to be a major pain to accomplish because of my tank setup. I may or may not see the type of fish I'm set on putting in my tank when I take them to the lfs.....so the tank might have to sit empty until I can get what I want (possibly through mail order).

If I keep the cycle going with some pure ammonia....will dropping that in the water in very small amounts hurt my inverts? If not how much would you recommend?

Thanks!!