Tropical fish are easy compared to saltwater fish. I'd trust someone who is familiar with saltwater fish rather than someone who only deals with fresh water fish. They are similar only in that they are fish, but the requirements are quite different. That being said...
If you have good live sand, and the live rock is fully cured, the tank may not even cycle... or it may just have a mini-cycle. If there's a feather duster living on it, chances are the rock is already cured. It would be a good idea to "ghost feed" the tank to be absolutely sure, as it's cruel to have a fish in the tank during a cycle. Just add a pinch of fish food to the tank once a day for a few days to see if there's an Ammonia spike. If there isn't a spike, then you're good to go. If there is a spike, wait until Ammonia drops to zero, do water change, and add a fish. One important piece of information... stock SLOWLY. Do NOT fill the tank to capacity immediately. Add fish gradually, so the bio system has a chance to adjust. It takes time for the beneficial bacteria to grow, so don't overload the system. Nothing good ever happens quickly in saltwater, but bad things can... and do. Be patient. The less you rush, the better your chances of success.