How to implement OOBE complete notification in c++?

I want to do a win32 implementation of RegisterWaitUntilOOBECompleted API for my app. The goal is to detect OOBE complete and perform specific operations.

However, I don't quite understand how to implement it in c++ code. I spent the past 6 hours looking for sample implementation but to no luck. Can anyone explain how to do it?

Registers a callback to be called once OOBE (Windows Welcome) has been completed.

Syntax C++

BOOL RegisterWaitUntilOOBECompleted(   OOBE_COMPLETED_CALLBACK
OOBECompletedCallback,   PVOID                   CallbackContext,  
PVOID                   *WaitHandle ); 

Parameters

OOBECompletedCallback

Pointer to an application-defined callback function that will be called upon completion of OOBE. For more information, see OOBE_COMPLETED_CALLBACK.

CallbackContext

Pointer to the callback context. This value will be passed to the function specified by OOBECompletedCallback. This value can be nulll.

WaitHandle

Pointer to a variable that will receive the handle to the wait callback registration.