This morning, AllThingsD’s John Paczkowski reported that Apple was set to unveil the iPhone 5 on October 4th. Paczkowski has a long history of breaking Apple news. Some even believe that Apple feeds him breaking stories from time to time. I guess my point here is that we can trust the guy.

Now that we’re pretty sure that the iPhone 5 will be showed to the world on October 4th, the question on everybody’s mind now is this: “When will we be able to purchase the iPhone 5?”

In his article, John Paczkowski says that the iPhone 5 will go on sale “within a few weeks” of the announcement. Pretty vague, if you ask me. That’s why Fortune looked back at previous iPhone announcements to see if we could learn anything from the past.

“But in a note to clients Tuesday, Ticonderoga’s Brian White suggests that the lag time between unveiling and release is likely to be considerably shorter than that, especially given how late in the year the iPhone 5 event is occurring.

A look at previous lag-times suggests that he is right. As the chart at right shows, the wait between iPhone introduction and sale has steadily decreased from 201 days in 2007 to 17 days in 2010.

Likewise, the lag time for the iPad shrank from 32 days in 2010 to 9 days this year.

White also believes that the international ramp-up for Apple’s 228 carriers will be faster than it was for the iPhone 4, and that China will play a more important role than ever.”

In the view of historical data, it looks like the iPhone 5 could go on sale within 1-2 weeks of the announcement. Time will tell.