The official Pokémon movie website has updated. Translations follow:

Media Information

Magazines:
Wednesday March 20th: "Corocoro Ichiban!" - Presentation of the movie poster & information on the pre-order ticket
Wednesday March 20th: "Nintendo Dream" - Presentation of the movie poster & information on the pre-order ticket

*Note that these are the scheduled publication dates, and as such are subject to change without notice.

Source: https://www.pokemon-movie.jp/news/?p=3605