This will be the first time I am taking a laptop through carry-on and was wondering if someone could explain what I have to do for security clearance? I think I have to boot it up prior to walking through, but can I do that ahead of time while I am waiting in line or do they have to see me doing it? Do I then put the laptop in the bin to go through the xray? Any help would be appreciated as I don't want to hold up the line if I can help it. Thanks.