I have recently changed (about 1 week ago) my url from non www version to www version.

I told my hosting company to do this and they did it successfully all my urls are directed to www version. But google is indexing my non www version on the search results. I have updated new content on my website and google indexes that content with the changed url i.e with prefix www but the mainpage i.e the site name is still shown without www and its not updated. I have checked that my `www.sitename.com` is listed on google but not shown when I type `www.sitename.com`. So how much time does it take to remove the old urls from indexing and updating into new urls ??????