To avoid bathroom breaks during the movie.
Go to the bathroom to make sure there is no lingering buildup to avoid unexpected surprise during the movie.
Do not buy any candy or snacks or beverages. I know it's tempting. What if you have to wait in the line to the bathroom? and when you are back over 20 to 30 minutes and nothing is making any sense.
What does matter the most? The snack? The candy? The beverages? The movie?