Hope I'll find the line on my first day then.. 
Don't worry the line is not hard to find. Before they open the doors there is just one line to get in the building(besides the Hall H line which is separate). Once you are in follow the crowd up the escalator and go toward the back of the building there are doors to go out and the Ballroom 20 line forms out there. They have people to direct you and if you meet people in line that are going there and have done it, just follow them.
Last year was my first year and I was worried about it too but it worked out fine and wasn't as difficult as I imagined. We lined up one night at 3 am and were 15th in line for Ballroom 20 but the next night we were lined up behind the Firefly crowd at 2 am but still got into the room. Good luck!