I applied and passed the exam and they said they would contact me in Feb. or March. I have not heard from them.
I worked with the census in 2000, but never took the test until about March of 2000. Some work had taken place before then, but most of it was during 2000, and I expect most of the work will be during 2010 thins time.
I plan to take the test soon. I know someone who's already taken it (who also worked in 2000) who hasn't heard from them yet. I really don't know how much work is done in the year before the main count is done.