I'm glad that you already have an Advanced Dining Reservation at Akershus set. It takes the pressure off because those reservations go rather quickly. In all honesty, I think that the last breakfast seating is as perfect as the first. Disney makes sure that each seating reflects the one before. I wouldn't worry about missing out on anything.
Really, it comes down to a matter of personal preference. Are you an early riser or do you enjoy sleeping in a little while you're on vacation? I enjoy sleeping in because we're a family of night owls and enjoy staying up late. Whatever decision you make will not be wrong. You'll still enjoy the full experience of your character dining at Akershus no matter what time you choose.