Feature Request How do I get the marker detection time in an AR android app?

Hello,
I am trying to compare the speed of marker detection in different android phones for different image marker types. How do I do this efficiently such that I can get the time between when the target is placed before the marker and when the phone camera detects it (and displays the virtual content)? I am using vuforia SDK plugin in Unity 3D game engine to develop the mobile app.
Thanks.