Is the lighting in your tank different than the stores? What type of flow was it in in the store... I would think you should have started to see some extension by now
Not necessarily. Just like some fish that you won't see for weeks after acclimation, corals will do the same. Gonis are no different and can be extremely finicky. Still give it some time. I'd say another week. If by then nothing has happened move it to a different area. Low light/higher light/low flow/higher flow of course depending on where it is currently. Don't change things all at once. Change one thing but not the other. No need to continually move it when it hasn't acclimated fully yet in the first place. To ensure success in keeping your goni, you need to baby it more so than other corals in my opinion.