Loading a scene with a long press!

Hey! Things to add to the code. I want to load the scene after 5 seconds of holding!
Can you tell me Please?

 public string [] SceneNames;

 void OnMouseDown ()
 {
     int s = Random.Range (0, SceneNames.Length) ;
       SceneManager.LoadScene(SceneNames~~);~~

}

private float mouseDownTime;

void Update()
{
     bool hasBeenClicked = mouseDownTime > 0;
     if(hasBeenClicked)
     {
         bool timeHasElapsed = Time.time > mouseDownTime + 5;
         if(timeHasElapsed)
         {
              int s = Random.Range (0, SceneNames.Length) ;
              SceneManager.LoadScene(SceneNames~~);~~

}
if(Input.GetMouseButtonUp(0))
{
mouseDownTime = -1f;
}
}
}
void OnMouseDown ()
{
mouseDownTime = Time.time;
}