When you start up a new Pycharm project or add a new interpreter, you have to let the index processes run (there's an indicator in the lower toolbar which will tell you when background processes are running...click it). When those index processes are finished, Pycharm will definitely autocomplete import statements: http://imgur.com/JRsfH
What version of IDEA do you have? The latest version 10.5 works with the new version of the python plugin (which is basicaly pycharm) and auto completes right away when you start typing.
I really don't like having to configure the interpreters but it's also nice when you're using project based virtual environments.