This is my third year at CES (I wasn't able to go last year) and the third time that I was able to get into the Convention Center a day early. I've used the same entrance every time and just acted like I was supposed to be in there once inside.
I always felt like I was going to get caught and thrown out in previous years, so I tried to move as quickly as possible. This time, however, I spent about 90 minutes walking around Central and South Halls. Despite having to dodge forklifts and step through construction areas, I actually found it to be pretty relaxing. It was nice to be able to look at stuff (albeit in various stages of completion) without having to deal with crowds of people.