According to Microsft in this article is should see an option ‘Code First From Database’ when adding a new item to the project under ‘ADO.NET Entity Data Model’ in step 3.
Where is it the component for Code First like following picture?
For installing in Visual Studio 2012 or 2013 this functions you can download the install for this link https://www.microsoft.com/en-us/download/details.aspx?id=40762