You will get the second letter 4-6 weeks before your interview is scheduled by the KCC.But the date for your interview schedule will depend on your case number. Interview process for the year 2013 begins on October. 2012. Mast probably for that month the case number up to 7000 will be scheduled for the Asia. It is better you keep looking the travel.state.gov to know when your case number will become current.....