jeffishere, welcome to FlyerTalk! As you'll get good help about your Big Island plans in our Travel->Hawaii forum, even though you have a Q about SNA, I'll move your post to our Hawaii forum. Ocn Vw 1K, Moderator, TravelBuzz.
(P.S. Unless you are arriving at SNA on a day likely to be crowded with those returning from Christmas travel, I'd think that 1h 15 mins. before departure should be fine without checked bags and about 15 mins. earlier than that w/checked bags.)