为父母申请绿卡

Really appreciate the help if someone can provide the information: How long does it take to arrange the immigrant interview after all materials being forwarded to GuangZhou?

I applied GC for my parents who are still in China in Nov 2002. And I was told that the application was approved and the materials were forwarded to GuangZhou in Feb 04. Then I was told that they are under name clearing process now but no one gives me an estimation about how long it will take. I really wish my parents can come before the end of the year. Does anyone have recent experience helping their parents/relatives get through the immigration process in China? Thanks a lot in advance.