You should implement the open graph in the live website. You can keep your application in the development mode till the application is approved.
While your application is in development mode, nobody but the administrators/developers/testers/test users can do posting and everything. For rest, the API calls will not be successful.
So you just have to do this- complete the og integration, create a test user-
test the complete flow and submit for the review explaining the steps with the test user. They will test it with the same test user and will approve it if everything is fine. Then, you can switch your application to [live]. That's it.
Hope it helps. Good luck!