Early boarding is almost always a challenge, and a wait. But it has its advantages.
If you wait awhile, but get on board early, you can do your muster, book shows, and eat lunch in the MDR rather than the buffet.
If you get there at 1:00, you will likely walk straight on board, but still have to do all that stuff and end up in a massively crowded buffet.
Your choice, but we'll wait awhile and get onboard as soon as possible.