Amanda,
Thanks for sending your question to planDisney!
Typically
Disney Transportation starts running 1 hour prior to the opening of the park where that transportation is headed. For you to get from
Disney's Animal Kingdom Villas - Kidani Village to
Disney's Riviera Resort there are a few routes you can take, but in any of these instances you will want to check with your resort front desk the day beforehand to confirm what transportation schedules will best match your desired route.
Option 1: If you take the bus from your Resort to
Disney's Hollywood Studios, you can then hop on the
Disney Skyliner to get to the Riviera. But with travel time estimated at about an hour, I expect that the buses to Hollywood Studios will not have started early enough for you to make your breakfast reservation.
Option 2: The quasi-official route to get from one resort to the other is to bus to
Disney Springs, and then to bus from there to the Riviera. This should be a shorter route, but you will absolutely want to confirm with the front desk of when the buses will start running.
Option 3: Disney's Animal Kingdom Theme Park typically has an earlier start time, and around your arrival date it looks like it will open around 7:30 am. This might be the best way to get to the Riviera. With a 10-minute bus ride from your resort to the theme park, and then about a 30-minute ride from there to the Riviera, you should be able to get there in time, assuming the buses start at 6:30 from your resort to the park. But you will want to be on that first bus at 6:30, as bus wait times for that second ride might be significant.
In your instance I would only consider options 2 or 3, though if the time of day were later, I would prefer the first. But your highest priority is to speak to your resort front desk the day before, or even earlier, to ask them how best to get from Point A to Point B. They can confirm times, and possibly arrange other means of transportation if they think that there is a risk you will miss your meal.
I hope that this helps, and that you have a great breakfast.
Have a Magical Vacation!
Doug