Hello Sarah,
I saw that you asked this question a few days ago. I don't use Cvent's Express Registration as much because I can't customize the Website, Registration, Reports and no Surveys available.
However, it is a great tool to quickly make a webpage and quick registration (with limited control). I couldn't find anything called Planning Status, but I did find Current Status and you can move the site to test mode (Perform Test) or even launch the event (Launch Event).
On the
Express Registration you would go to
Overview (tab) then on the right side is how you would change the status of the express registration.
If this didn't answer your question, please be a little more specific on what you need exactly.
Good Luck!