Sorry, I am sticking to my guns here. The only time I arrived at a terminal early (about 10:45) it tooks us 90 minutes to get onboard - yet when I get there later in the day I generally get onboard almost right away. Plus there is nothing to do on the ship early on, and you have to carry your bags with you because your cabin isn't ready.
The idea of arriving early may have worked a few years ago - but in the last year it has gotten out of hand and that is when the rush is....
It may depend on the size of the ship and terminal, though.
Try what you want, though.