At all my theaters, commercials are played when the movie starts. You'll go to an 8:00 showing, and you'll see ads for Coke, Playstation 2, and Jeans. The Playstation 2 ads are hilarious, because all the games look like crap blown up on the huge movie screen with the set resolution. And the Jeans and Coke commercials are so dumb...they often last for a minute or two, and they take themselves way to seriously. Lately, I keep seeing ads for Fandango too, but I don't mind those as much because
www.fandango.com is actually a resourceful website.
So, after 5-10 minutes of commercials, I get to see previews. Usually, I can get by walking into an 8:00 showing at 8:15. Especially once the movie has lost momentum and seating isn't a big issue.