I find it bad etiquette to fill the aisle with your bag as this prevents others from being able to get up and ready to depart. It seems really easy to prep your bag when you put it up such that you can grab it and go as soon as you can start moving forward. The two seconds that takes, gives someone else the opportunity to be ready and set to deplane, which is >2 seconds.

Just my opinion, but I have a tendency to over analyze . . .