https://www.google.com/adsense/support/bin/answer.py?hl=en&answer=35870
As you can see in the above link that your Adsense pin will be issued once your account balance reaches $10 for the first time and you should receive your Adsense pincode within 3 to 4 weeks at your address depending upon your location.
New Adsense publishers get so much excited about it and the start checking mails and some also visit post offices asking about mails from Google Adsense. The excitement soon converts into anguish and they start worrying about Adsense PIN with the passage of time.
With a mixed feeling of excitement and anguish they decide to email Google Adsense Support but they get an annoying AutoResponse emails stating that we have once again sent you the PIN which you will get it another 4-5 weeks which further aggravate this situation.
After getting a lot of Emails you will finally get this Auto Response email.
