First, being early or even the earliest doesn't guarantee that you will be first on Peter Pan (or other popular ride). On a EE day, you'd have to out "walk" everyone else from the gates all the way to Fantasyland. On other days (or if you don't have EE), the race usually starts at the ropes.
The question nobody asked is - "Can you really be first in line for a turnstile?" - the answer is "sorta", "kinda", "maybe". My experience is with DLP, but I've seen basically the same thing as DCAP.
There isn't one single sign in front of either park about how you are to line up. Generally, people park themselves in the middle of gate, so are more in line for that gate than for either turnstile. Occasionally, one or two might come up and clearly stand before a turnstile. Disney doesn't even try to control how the lines forms. The vast majority of them look will like one messy line per gate before they are opened.
Now, it gets even weirder. There was a period of about a year when CMs would tell guests to split into two lines (that is, one per turnstile) a couple of minutes before opening the gates. Then, I noticed that this was not happening on some days, and that only half of a gate would be opened, and people would split off after passing through, using one turnstile or the other. I guessed this had to do with the picture taking, which was simplified with fewer lines for the CM to work.
