You will find offerings from both most likely. If you are seated on time. It's very possible there will be enough of a delay (we've waited more than 30 min twice when eating at TH) in your seating that the breakfast offerings will be removed by the time you are seated and head to the buffet.
But they condense the breakfast offerings to a small area of the buffet and start to bring in the lunch choices. If breakfast is very important to you it may be worth trying to move it up a little.