Planning an event can be a complicated process, but you have plenty of resources available to you to help out, whether you're representing a club, or are organizing something as an individual student!
Review the Event Calendar to select a time and date for your event.
If you want to book an event during another event, consider: will your attendance be low due to attendance at the other event?
You should also consider the academic schedule when selecting a time and date, as well as the audience you're looking for - when are breaks in the semester? When are midterms and finals? When are the lunch periods for each class?