On a normal day, when the park is scheduled to open at 9, 8 or 8:15 is pretty early (unless some really crazy people are visiting)... On an Extra Magic Hour day (Sun & Thu), when the park opens to day guests at 8am, 7:30 is early (of course, if you're not staying on-property, you won't be able to get to the park entrance that early on those days). Of course, I should point out that Grand Marshalls are not usually picked at the entry plaza. At MK, it can happen anywhere (usually Main St) in the morning after the park has opened. It is done entirely at random (unless it's some celeb)... So showing up extra-super-kids-are-cranky/asleep-early really isn't necessary (and I don't *personally* reccomend it)...