I would not bother doing this.
Not least is the issue of your actual seat in the restaurant. Trust me, they know you want the window seat in Tokyo Dining. They also know you want the patio tables at Rose & Crown. They are wise to you. When you get there, they're 99 percent likely to seat you at a table without a view (as most tables do not have one). Also, if your reservation is more than 1 hour before the show, they will incessantly remind you (certainly Rose & Crown does) that you are to eat and leave, and not linger.
We had an ADR at Rose & Crown at 4pm last trip. They put us outside on the patio, but reminded us probably 20 times during the 1 hour (yes, we were only there for ONE HOUR) we were there that we had a time limit on the table and we could not stay. (Honestly who would camp a table for 5 full hours waiting for the 9pm fireworks? I have better things to do in 5 hours at EPCOT, but clearly it's a problem, or they would not be harassing people at 4pm.) The hostess who seated us, the table server, and random people filling water glasses reminded us constantly that our table had a time limit. Frankly the experience was annoying and offensive enough that we decided not to return to R&C, and if we ever change our minds about eating there, we will insist on an inside table so we can eat our meal without being bugged about leaving before we've even ordered our food.
If you do get lucky enough to have a seat with a view, prepare for half the restaurant to crowd your table so they can see, too. (Yep, that's happened to us too, complete with somebody's kid coughing into my food.)
Recommend you just find a nice spot to watch about 8:30 or so - there are many good spots around the lagoon. They drag the barges out there and start prepping their fireworks midafternoon so you have plenty of time to decide where you want to watch from and gauge the view before returning there later!
