Short answers, pulled from the story.
The phrase appeared in a London Evening News advertisement on Thursday the 3rd of May 1979. The Conservatives party used this half-page ad to support Margaret Thatcher before election results were counted.
The first organized celebration took place in Toronto, Ontario, Canada at the Toronto Underground Cinema in 2011. Sean Ward and Alice Quinn produced the event which included trivia games and costume contests.
The Walt Disney Company has officially observed the holiday since 2013 with events at Disneyland and Walt Disney World. They have released multiple titles including The Clone Wars finale and Star Wars: The Bad Batch on May 4 dates.
May 25 marks the anniversary of the original Star Wars movie release from 1977. The Los Angeles City Council declared the 25th of May 2007 as Star Wars Day to honor that milestone.
Some recognize the day after May 4 as Revenge of the Fifth playing on Episode III: Revenge of the Sith title. Others celebrate this one day later on May 6 citing Return of the 6th as a better pun on Return of the Jedi.