California Grill opens at 5:00. All the window tables will most likely be filled with people who have ADRs between 5:00 and 5:30. We've been twice, with 5:15 and 5:30 ADRs respectively and got MK view window seats both times; we checked in early and didn't request the tables, but were happily surprised. We got very lucky. By 5:45, if not sooner on both occasions, all those tables were seated. It's also unlikely any tables will be turning over before 6:00, though not impossible. So I don't know that a 5:50 ADR will get you what you want. You probably have a slightly better shot at 7:00, but even that isn't great odds. Dinner at California Grill takes a while. People linger and many ask for window tables. All that being said, I'd do as others have suggested and focus on seeing the fireworks from the viewing deck. It's actually better outside than from inside with the glare of restaurant lights and chatter of diners. Choose the ADR time that works best for when you actually want to eat and enjoy your meal!