According to the Los Angeles City Council, the official Star Wars Day is May 25th (commemorating the anniversary of the film’s opening on May 25, 1977). However, since that is also Geek Pride Day and Towel Day, more and more Star Wars fans have adopted the Fourth as their own.
As an exercise:
Which date is important to your main character? Is it their birthday, graduation day or the day they will be released from prison? Is it an upcoming date or one in the past? Why is it important? What do they do to celebrate/remember it?