I just stayed there for 2 nights a few weeks ago and this was very confusing to me. They say that hotel guests can get in a half hour early, that only certain rides were open, and they give you their version of a pin to proove you are a hotel guest. But it seemed to me, that they were just letting anyone who made it there at that point in and most rides looked to be open! There was no special line or gate, nothing holding anyone back and not everyone had the button on (well, they only give one per kid, but still, i saw kids without them). I think that the crowds are no big deal to them that early in the morning, so they don't really care if they're hotel guests or not. I mean, we returned 4 days later and got there about noon and tons of people were arriving at the same time. I just don't think they have people clamoring to get there before park opening like DLR does.
It's possible that I missed whatever they do to separate who is from the hotel, but it was all so casual compared to DLR, so I doubt it.
So, I'd say just go at the early time and walk in. Worst case, someone runs over the 10 yards to the hotel and checks in real quick while everyone else hangs in the coffee shop/lounge and the kids play in the castle that's right there. It's all so close, it wouldn't be a big deal at all either way!