You mean for the Zurich Salsa Group? The last was last night, and the next one has not been planned yet. I'd say just register at the meetup and you will receive a notification as soon as the next night is announced.
As for my own parties, the next one is planned for late autumn, although I will only start working on it in september because of my holidays this month.
If anybody has a suggestion about a good club to host the event, please feel free to tell me (it just has to have enough space to dance and wooden floor would be nice), it can be zurich or zug...