These days, when I have a movie ticket for time T, I plan to arrive at T+20 minutes. That's when the ads are over, roughly when the trailers are playing.
Pick your ticket online, show up a few minutes earlier, enjoy a decent appetizer, and get a drink or two while the movie is on. Whatever floats your boat. I find it's a much better experience and frankly not that much more expensive than sitting through hell my local multiplex
This way, when you make your seat selection, you can choose if you want the convenience and slight distraction of waiters, or if you just want the comfy chair and no waiter.