Op, since you already changed it, you're all set. For others in such a situation, you can always check in early, go to the factory tour, then return to delivery later. The paperwork can be done much earlier than the actual delivery time. One thing to note though is the English speaking factory tour, that is only held at 11:30am each day, so don't miss that. I just got back from my delivery date on 7/19 where I had a 10:30am appointment, and we went beyond 11:30am, so I had to wait until the next day for the factory tour.
You'll love it, between the Welt, Factory tour (which does go the full 2 hours), and the museum, expect to spend the full day at Olympiapark :thumbup: