There is a rule of thumb. After 2nd fp, your i485 will be approved very soon.
I saw a lot indian guys share their waiting information around. But I didn't saw we Chinese.
Why not join them?
I saw forum like this. You can put your waiting information onto one tracker. They will update your information in a Excel file. Pretty cool though.
http://www.immigrationportal.com/forumdisplay.php?f=98