Adoption tax credit qs

I'm currently searching the forum for an answer on this...but there's so many posts on the subject, I thought I'd see if anyone can help in the meantime.We had a long wait for our little guy. He was placed with us in Jan 2011 but our fees were all paid out in 2007.We were under the impression we needed to wait until the adoption is finalized to claim our tax credit. If we do that though, we won't claim until 2012. Is this correct, or should we file an amendment to our 2008 taxes this year and get the refund?