13 days is the time taken to get the results, then add the number of days for the mail to arrive depending on your residence from the place you took the IELTS Exam. This was what told to me when I took the exam on 9th May 2009.
go to the link in the previous post and enter the required fields like your IELTS id number etc. the whole page is pretty self explanatory and your scores will be available for you to view upto a month after you sit the exam.