Some corals are much slower to settle in and open up. I've found Duncans can even take a day or two. Some leathers can take a week or more before they put out polyps. The slowest I've ever experienced is a Blue Ridge coral, it took several weeks and even then only puts out polyps occasionally!
I got a frag that looks almost exactly like yours about a year ago. It was shy for about a week or so. Mine likes a lot of flow and low in the tank. It did not grow real fast for the first few months but recently it has been growing new polyps(?) and looks to be around 7-8 of them. It seems to a very tolerant coral as far as movement and small parameter swings. When it is disturbed significantly(touched) it will close up for hours to a day before opening back up, but it ALWAYS does. It has been a long time since its been bothered but I remember being concerned when it would stay closed for a while, so I am pretty excited to see it multiplying.
Yours looks perfectly healthy. It is what mine looked like in the morning when the lights just come on. I agree with the others, give it a bit more time.
Also, they seem to love mysis. When they are fully opened, I feed all the poylps/heads(?) and they respond well.