I never line up super early. I meander in casually once the line has died down. When dealers tell you stuff sells out in the first hour, I'll tell you what it is:
whatever hyped-up anime is popular that year, they will sell out of the already overpriced merchandise.
I'm not one to line up for 4 hours to get robbed, lol. As I've pointed out elsewhere, 90-95% of the stuff you find in the dealers hall is available online for a much better price. I much prefer swap meet/artist alley in that respect.
But hey, to each their own.