Buy some test kits...Amonia, Nitrate, and Nitrite. These should give you a good idea of when the tank has cycled and is ready (safe) to add fish. If you have any amonia in the tank at all then something is dying off and you need to address that. It may be that the LR had some sponges that died when exposed to air. Water changes with aerated water and patience.
You really don't need any fish to cycle the tank. Just put a piece of shrimp from the store in the tank (rinse it first to remove the phosphates used to preserve them). This will provide plenty of bacteria to start the cycle.
Once your amonia and nitrites are at zero, start monitoring the nitrates. You want these to be low to zero on the test kit. Once you get to this point you should be safe adding a couple of fish. Add slowly and monitor the Nitrate levels.
The key is consistent parameters. Salinity, temperature, lighting period, nitrates, etc...all need to ramain as consistent as possible which is why Ed suggested the timers for the lights.
Good luck and keep asking questions...we'll get you rolling.