The preview release version of SSDT for Visual Studio 2017, should not be used for production environments at this point. An RTM date is not available at this point, but seems to be closer now that a preview is available.
The link below will redirect you to the download page.
Download SQL Server Data Tools (SSDT)
The release number is 15.3.0 preview, but the build number for this release is 14.0.16121.0
SSDT for Visual Studio 2017 has the same system requirements as installing VS, supported operating systems are Windows 7 SP1, Windows 8.1 or Windows Server 2012 R2, Windows 10 or Windows Server 2016, and is currently only available for the English Language.