all fish are different. some go right for it, some it takes some time, and some not at all. you'll just have to wait it out. is it a true perc or false perc? you have a better chance of it hosting if its a true perc. i have a false perc and that idiot hosts my xenia and ricordea mushrooms. but like i said, only time will tell.
if its suggestions your after, you could try printing a picture of a clown in an anemone and taping it to the side of the tank. maybe it will give your guy some ideas.