Originally Posted by
ksandness
I've arrived in Japan, spent a week or two in Tokyo or Kyoto, and then validated my JR Pass (doable at any major train station) for journeys around the country. Your pass is valid for 7, 14, or 21 days from whenever you validate it, not from your arrival in Japan.
Just to be clear -- The list of stations which have offices that can exchange a JR pass voucher for a JR pass is here:
http://www.japanrailpass.net/eng/en009.html
The pass does not necessarily have to start on the date you validate it. When you visit the JR pass exchange office, you can specify the date on which you wish to start using it. That date can be days or even weeks later.