How long for a held ball?

[Loudwhistle]

I tend to hold my whistle a little longer during Gjv, they sometimes can get the ball away from opponent without us having to stop the game. In physical, rival, BV games I hit the whistle very quickly to stop the rip the ball away and maybe take out somebody's teeth with an elbow. I sometimes sprint right up to players while blowing my whistle on a held ball if I know they are cocky.