I'm of the opinion that your tank will be a lot more stable starting out if you let it go through a full blown cycle. That way, you KNOW that you've got adequate bacterial growth to handle the bioload of fish.
I bought cured live rock when I started my 14 gallon nano, but I still tossed a piece of raw shrimp in there to cause an ammonia spike. Even with the cured live rock, it still took a month for the ammonia to drop to zero. If I hadn't done that and had assumed that the cured rock had enough bacteria to handle a fish, it would have likely spelled death for whatever fish I put in there. Better to be safe than sorry.