dont be surprised if it moves onto your overflow or glass..mine went to the glass no matter what I did in the tank..it loves it there ,right under full strength LED's and right near the outflow of an HOB...the clowns dont seem to like it their home is hanging off the side of the glass kinda tilted towards the light...I am moving mine into a bigger tank soon...so we'll see what it does with more flow and less chance to climb the glass...
i would highly recommend you move it to your rockwork, and make sure your rock is separated from your glass. this will help keep your anemone in place AND away from walking up to your overflow.