All Things Digital‘s John Paczkowski reports that Apple (AAPL) plans to unveil the new iPhone at a special event on Tuesday Oct. 4.

If so, when can we buy one?

Paczkowski’s sources say “within a few weeks.” 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 decreased from 171 days in 2007 to 17 days in 2010.

Likewise, the lag time for the iPad shrank from 66 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.

Everybody seems to agree that this will be Tim Cook’s first big show. Some have suggested that Steve Jobs might make a cameo appearance. That doesn’t sound to us like something he would do.

NOTE: An earlier version of this story described Paczkowski as “Apple’s current go-to outlet for backchannel leaks,” implying that the company either gave him the information directly or channeled it to him through a third party. He resents the implication and assures me that this is not the case. I’ve deleted that language and offered my apologies.