Note that Ray Park (Darth Maul) is doing only one signing session per day, at 1:00 P.M. While the session is 90 minutes long, some guests end up taking longer than normal if they start a conversation beyond mere pleasantries.
The line cut-off for Ray Park was somewhere between 2:00 and 2:30 A.M. this morning. He is returning Saturday and Sunday as well as next weekend (June 12, 13 and 14th), so there are more opportunities to meet him. Just be sure to arrive early.
By contrast, Jeremy Bulloch (Boba Fett) has higher capacity. He has three signing times (1:00, 2:15 and 4:30 PM) Fri/Sat/Sun, and is not as loquacious/talkative, so his line moves more quickly. Bulloch is not scheduled to return next weekend, so you are still advised to arrive early (no later than 5:00 AM) if you wish to meet him.
Disney’s Hollywood Studios opens at approximately 7:30-7:40 A.M.