My husband and I discussed it. We talked about the pros and cons, what we would do if he freaked out, etc. We talked about it with Monster. If the movie scares you, we can't fast forward. The theater is dark and we can't turn on the lights. We can't stop the movie to go to the bathroom. We prepared the hell out of him for his first movie theater experience. We even read the Cars 2 books when they came out so we would have the basic plot.
Even after all the prep, we really weren't sure how he would do. We got a sitter for Sunshine and we headed off on our adventure. Monster could not stop talking about it. He was so excited and a little nervous. "Just like when I go to a new school or class, Mommy" was how he decided how he was feeling. As we head in, Monster is quiet and perfectly behaved. He's in awe of the whole thing. We get popcorn (at 10am...not really a breakfast food) and head on in. We find seats and get ready. My kid was great. He was literally the best one there. He sat. He watched. He asked questions quietly when he needed to know something. When the movie was over, he was so proud of himself. He was thrilled he got to see it AND he loved it! He asked, "Can we watch it again?".
I'm pretty darned proud of my little Monster. He's growing up.