Yeah, you gotta fight your rival in Kiloude, then you should get a call from Sycamore, then go to Anistar, get a Mega Ring upgrade and THEN be able to find Random Mega Stones lying around. Between 8 and 9 PM only though, so you might wanna use a guide to gather them all quickly.
EDIT: Tonton, you blind man? http://www.serebii.net/xy/friendsafari.shtml