Hi Nellie, and welcome to the DIS!
Table location doesn't matter (unless you want to be close to the buffet tables!).
The characters rotate around the restaurant and eventually all of them will get to your table. In some cases two or more will come to your table at the same time. They'll stop, pose for pictures, sign autographs, and amaze you with their "non-verbal communication skills." It's a science that Disney has perfected.
You'll want to make an ADR for both of those rather than "getting there early." Those are two very popular character meals and you may not be able to just walk in.
Enjoy!
Bob