Never been there. It's actually only 1 mile from my house and is there since 2 years but I've never been there during launch time.
If I were to make a wild guess, I'd say at least a week.
But then again, the one in Amsterdam, 15 miles from me, is busy all the time. Some Stores never die down
Depends on what counts as part of the rush.
During the iPhone 6 launch in London, the Apple Store had a queue and crowd that lasted until 6pm on launch day. It was more crowded than usual for the following weeks, but no queues.