Here some info from the studio regarding where you can pick one up:
"The posters can be found at the Wondercon Freebie table throughout the show. KROQ will be giving them away on on-site Saturday (March 29th) from 4pm - 7pm. Additionally, they can look for the Ender's Game team that will be wandering in areas outside of the convention center. "Any lucky Launchies attending WonderCon this weekend? Feel like sending us some photos? You can reach us anytime at email@example.com.
Good luck, guys. Let us know what you find!