My understanding was that when you made your reservations 2 years in advance, your seating was based on how early you made your reservations.
I was told yesterday by a dining CM that it is no longer based on that, it is based on where your family fits into the table layout. I have to admit that made more sense to me.
I also read that it mattered how early you pick up your tickets that day but that did not make sense to me.