Well, your only options are to get stronger lights, as soon as you can, return the anemone to the fish store before it dies, and then nukes your entire tank, or just keep it and see how it fairs out, which more than likely will not be good. Especially since the tank is not cycled. Water fluctuations will be prevalent, and anemones absolutely hate unstable water conditions. Sorry to say..
I think the first signs you should be looking for are the anemone constantly moving around, deflating, and then trying to hide under rocks. Although, it will most likely be moving around constantly, and trying to get as close as it can to your lights.