I filed my AP application on March 13, but the receipt date was March 27, 2006. I was worried since I need this document to apply UK visa and leave date is June 24. I was told the application would be transfered to local office since my I-485 was transfered there. And indeed my hu*****and AP application was transfered and got it more than 3 months. Surpprisingly, I received my APPROVED AP yesterday, directly from NSC. It seems that it is not necessary for AP to be tansfered to the local office although I-485 was transfered.
I just want to share this information to you, and also want to thank Xiaobaitu, Mytwocents and the other people here who helped me.