Still Microsoft doesn’t release the Office 2013 officially, but they release some preview version of the upcoming product. The expected day of Office 2013 release date may at the end of last quarter of 2012. You may read the review of Microsoft Office 2013 before download the preview versions.
Office 365 Home Premium
Office 365 Small Business Preview
Office 365 Pro Plus Preview
Office 365 Enterprise Preview
Microsoft Office 2013 Download Preview Version
How to download Microsoft Office 2013:
There are two different ways you may download Office 2013. One is direct from Microsoft server using your Microsoft ID and second direct download mirror from without ID.
Download with ID
1. Go to http://www.microsoft.com/office/preview/en
2. Press Sign Up tab and choose the version to download
3. Log In with Microsoft ID and download automatically starts
4. Choose the location and setup Office 2013