It takes 6weeks to ship product from Corning's US factory to China.
‘I Want a Glass Screen’
In 2007, a little over a month before the iPhone was scheduled to appear in stores, Mr. Jobs beckoned a handful of lieutenants into an office. For weeks, he had been carrying a prototype of the device in his pocket.
Mr. Jobs angrily held up his iPhone, angling it so everyone could see the dozens of tiny scratches marring its plastic screen, according to someone who attended the meeting. He then pulled his keys from his jeans.
People will carry this phone in their pocket, he said. People also carry their keys in their pocket. “I won’t sell a product that gets scratched,” he said tensely. The only solution was using unscratchable glass instead. “I want a glass screen, and I want it perfect in six weeks.” †
This is a anecdote that now seems to be repeated as fact, but I have serious doubts about it. For starters there was a six month gap between the first demo and launch, and the iPhone was demoed with the glass screen, as evidenced by this quote from David Pogue from January 9, 2007 Apple went through numerous iterations of the glass surface, trying to find one that’s not too slick or too rough, or that shows grease and fingerprints too much. ††
† http://www.nytimes.com/2012/01/22/business/apple-america-and...
†† http://bits.blogs.nytimes.com/2007/01/09/some-hands-on-time-...
http://www.ilounge.com/index.php/news/comments/apple-upgrade...
"Apple also announced that the entire top surface of the iPhone, including the 3.5-inch screen, has been upgraded from plastic to optical-quality glass for better scratch resistance and visual clarity."
And they could build a factory anywhere in the world. In the mean time, they can ship as fast as they need. Apple already ships from the factory nearly directly to customers in the US in a couple of days.