The official Pokémon movie website has updated. Translations follow:
Media Information
Magazines:
Saturday April 21st: "Corocoro Ichiban!" - Presentation of the new Pokémon and characters that appear in the movie, etc.
Saturday April 21st: "Saikyo Jump" - Presentation of the new Pokémon
Saturday April 21st: "Dengeki Nintendo" - Presentation of the new Pokémon
Saturday April 28th: "Pokémon Fan" - Presentation of the new Pokémon + free stickers
Saturday April 28th: "Pucchigumi" - Pre-screening announcement
Saturday April 28th: "TV-kun" - Presentation of the new Pokémon, etc.
Saturday April 28th: "Kindergartener Magazine" - Pre-screening announcement
*Note that these are the scheduled publication dates, and as such are subject to change without notice.
Source:
http://www.pokemon-movie.jp/news/?p=3256