Unfortunately patients is something that you need when cycling an aquarium. I would strongly advise you to cycle your tank using a small shawl of tiger barb, or maybe danios, don't use your Oscars because they don't really like poor water conditions, during the cycling process the fish are going to be exposed to ammonia.
Adding water from a cycled tank isn't going to make a great deal of difference but it certainly worth doing as there will be some bacteria contained in the sand.
I am a little confused, is your 55 gallon tank still running with all your fish still in it?