And as it happens, all three were spotted in London over the weekend, just ahead of the official May start date for production.
Hamill, who played Luke Skywalker, posed with actor Peter Serafinowicz, the voice of Darth Maul in Episode I.
Harrison Ford chatting to the pilots of London's Air Ambulance in Grosvenor Square https://t.co/YJqX3KscBh— Matthew Bell (@kertappa) April 26, 2014
"So my do dog Gary has been spotted in London, but apparently without me. Who has he been seeing? Let me know if you have any clues," she wrote.
As for the rest of the cast, Walt Disney CEO Bob Iger has said moviegoers can expect to see "a trio of new young leads." Rumored names include Adam Driver (Girls), Lupita Nyong'o (12 Years a Slave) and Jesse Plemons (Friday Night Lights).