If you don't want to arrive early, you can arrive any time that fits your schedule.
I recommend arriving 45 minutes before the posted time, as there have been many cases at DHS, DAK and Epcot when they have allowed guests into the parks
as much as 30 minutes early.
Also, with multiple transportation variables, very few guests can accurately gauge exactly when they will actually arrive at a park's gates.
To set an earlier arrival goal can offset an unanticipated delay.
My assertion is that it's better to arrive far too early and wait a bit, than to get to your goal just a minute too late and be stuck behind slower entrants.
Others may disagree, and I've read those posts, as well.