Office 365 First Release - How to enable

Content from: http://office.microsoft.com/en-us/office365-suite-help/office-365-release-programs-HA104204958.aspx

With Office 365, you get product updates – like new email features, more site storage, and new collaboration features – as they become available. You can decide when to receive the updates by opting in to the First Release program or remaining on the Standard Release program.

First Release
Refresh
With this option, you and your users receive a select set of significant service updates as early as one week after the official announcement. Choose this option if you and your employees are comfortable with regular updates to the Office 365 service.
Standard Release
Calendar
With this default option, you and your users receive a select set of significant service updates 3 weeks or more after the official announcement. For at least 3 weeks, you have time to learn about the updates and prepare your employees.
 
Note    The Office 365 updates described in this article apply to the Office 365 suite, SharePoint Online, and Exchange Online. They do not apply to Lync Online, Exchange Online Protection, the latest version of Office and related services.
 

Turn on First Release

By default, all Office 365 accounts are on the Standard Release program. They receive service updates 3 weeks or more after the official announcement. You can remain on this update schedule or turn on First Release by following these steps.
  1. Sign in to Office O365.
  2. Go to Admin > Service settings > Updates.
  3. Turn First Release on or off.