HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Explorer
REG_DWORD – DontShowStartMenuOnLogin
1: Enable
0: Disable

If you enable this setting, the user will see the desktop after logging in to a new session, instead of seeing the Start menu or Metro UI. The Start Menu will continue to function as normal, except that it will not show automatically after login.

If you disable this setting or do not configure it, the Start Menu will appear after the user logs in to a new session.