Early morning in MK is pretty magical. We used to do pre-opening breakfasts (8am before a 9am open, for example), or use Crystal Palace for a lunch or early dinner. But the pictures and the ability to walk around a relatively empty park is priceless.
Our kids, now 7 and 11, were the same way! CP was a must, but unless we could snag a breakfast an hour before park opening, and take pictures on empty main street, we'd rope drop/early open and then go to CP for lunch or dinner. My parents, who are veterans of Vegas casino buffets, used to book the last breakfast reservation of the day to pay a breakfast price for breakfast and lunch foods. (I know). I have no idea if the prices are different but a late AM lunch worked very well for our family, especially if we were up early.