You can enable Google+ for all or just specific users at any time. However, note that Google+ is enabled automatically if all of the following apply:
- Your Admin console is configured to automatically add new services when Google releases them. (In the new Admin console, the setting is under Company Profile. In the classic Admin console, the setting is under Domain settings > New Services.)
- You have Google Apps or Google Apps for Business.
- Google Drive, Google Calendar, Google Talk, and Picasa Web Albums are already turned on for your users.
Remember: Even after you enable Google+, users still need to join the service before they can use it. Go to sign-up page
Ensure that the following services are turned on for organizational units with Google+:
Google Drive, Calendar, and Talk, which are listed under Core Google services. If any of these services doesn’t appear there, you’ll need to add it to your organization’s Google Apps account. Learn more
Picasa Web Albums, which is listed under Additional services.
After you enable Google+ and users join the service, they'll see the Google+ link in their Google menu bar at the top of Google service pages, such as Gmail and Calendar. For example: