According to “multiple” sources of the site HitFix, they have “confirmed” that Star Wars: Episode VII is set to start shooting mid-May & will run all the way through September of this year.
The report also says that “most principal casting on the film is complete.” Also, the writer mentions that he’s heard “that pretty much everyone who could make a return will make a return.” He says, that he hasn’t had it “confirmed conclusively, [he] thinks that even includes Lando.” As in Lando Calrissian.
Since neither Disney/Lucasfilm, nor J.J. Abrams have confirmed any of this, it will remain a rumor until then.
Last month, Carrie Fisher (Princess Leia), told TV Guide that she, Mark Hamill & Harrison Ford, are expected to start shooting in March or May. I’d take her word over some unnamed “multiple sources” any day.