The registration staff have taken great pains to make Door registration as quick as possible this year. We are planning on having 4 stations for door reg alone and the process should go smoothly once they get going. I can't make any guarantees of course, except for one.
The Door Registration line will be in the shade this year.
As for when to get in line..... registration will open at 8am, the first people got there at 6am last year I think. A big part of it depends on whether you're going to be staying at the Hilton (or in Vancouver at all really). If you have to commute don't get there too much earlier since you won't have the luxury of taking shifts and lounging in the room.
From what I've seen, the con opens at 8 but there'll be a couple of hours for the lines to go through before main events and the rest of the programming really gets into full swing.
Anyway, my personal recommendation is that you get down there at 5:30 with a folding chair, a manga, and a cup of coffee.
Then again, I camped out for three days for Return of the King and Star Wars Episode 3....and nobody else showed up for those until the day of the showing....