Steps to Check Original Installation Date of Windows

Step 1:

 Hold Windows key and Press R key to open Run, Type CMD and hit enter to Open up Command Prompt.

Step 2: 

Type systeminfo.exe in Command Prompt and Hit Enter.

Step 3:

 Just wait a Few Seconds to Gather all the Data , Boom- You will Get all the info of your System in just a few seconds including the Original Installation Date which we are looking for.

Step 4:

 With this Command you Get all the Necessary info about your System but If you know the date on which your windows was Installed on your System then type this Command systeminfo | find /i “install date