Gotta know you market and demographics.
Portion size and cooking loss.
Then be prepared to gamble and take a loss or hopefully a sell out.
Generate facebook and other social media connections by reminding every customer to follow and like you and to keep a lookout for the next event and spread the word.
I'd rather sellout and go home happy but on the other hand cook light and get a bunch of customers who think you can't handle the crowd and maybe dont show up next time or it makes it that much more competitive and people get in line early for your q
Best of luck and keep us posted.