You can only do a Mist Attack after the first one if you have one that's lighted up at the bottom right corner and has a corresponding button beside it for you to press.
IF there isn't one available you press R2 until there is one, you may have to press multiple times or one time and sometimes you'll press it until the timer runs out and you still won't have gotten one.
anata wa wakarimasu ka.....
Actually i should correct myself i wrote my previous entry a while ago lol and i now have 52 hours logged.
The weird thing that some people are doing is only levelling up 1 or three people in their party which a think is a bit lazy i think you should level up all characters if your going to do the game do it properly i say.
My highest is 30 my lowest 25 i have 2 espers and 12 quickenings and have done 13 hunts