when is the next championship

I guess it depends on what "Championship" you are referring to.

FFG Open series has Naboo in Syracuse and Tatooine Spain March 18-19. Hoth Chicago is March 23-25

https://www.fantasyflightgames.com/en/x-wing-open/

World Championships are in May and registration opens Noon tomorrow (March 14)

https://www.fantasyflightgames.com/en/news/2017/2/28/2017-may-world-championships-registration/

thanks

Noob question. I came to the game late last year just after Worlds in November so I was a little surprised to see Worlds coming up this May. Are there two world championships per year or did they just move up 2017s to May?

They moved all Star Wars games to their own World Championships starting this year.