There have been six theatrical releases of the Star Wars movies, and no, this does not count the re-releases that came in the mid 1990s. Aside from continuing the same narrative, another thing these films have in common is that they were all released in the month of May. With the (rumored) news of J.J. Abrams beginning principle filming in the near future, the idea of a May 2015 release remained strong. That idea, however, has come under fire after a convention no-show and a distinct lack of information available. Hell, even Conan O'Brien tried to do something about this lack of Star Wars news.
Here's another rumor for the pile involving Episode VII's release date, courtesy of Badass Digest:
Multiple sources have told me that right now Disney and Lucasfilm have December circled on their calendars, with a mid-month release - the 15th - being most likely. That would take Star Wars out of the crowded summer and, more importantly, give JJ Abrams and company a couple more months to work on a movie that's already running a tighter schedule than most of the other Star Wars films.
Concerning Disney's busy 2015, Slash Film pointed to six movies that Disney has provided solid release dates for. These include Ant-Man (November 6th, 2015) Avengers: Age of Ultron (May 1, 2015), Cinderella (March 13, 2015), Finding Dory (November 25, 2015) Inside Out (June 19, 2015), and Pirates of the Caribbean 5 (July 10, 2015). Apparently, the only 2015 Disney tentpole release that doesn't have a firm date is the new Star Wars movie.
In analyzing the new rumor, Slash Film points out the following:
Also, a December release date would move Episode VII out of what’s shaping up to be the most crowded, blockbuster summer of all time. Not that the film wouldn't easily be the highest grossing movie even with incredible competition, but December would also mean it could play well into January and February. That strategy lead Titanic and Avatar to each being the highest grossing films of all time, a goal that’s likely on the minds of Disney executives. The summer release, while more traditional, wouldn’t let them to stay on as many screens for as long.
Again, this is all speculation, and there's no guaranteeing the rumor will become anything more than that. Considering every other Star Wars release has come out in May, it's hard to see them deviating, no matter how crowded the 2015 summer lineup is; but then again, some casting news might help alleviate any doubts.