"How long does it take to become free of identification with the pain-body?

It takes no time at all. When the pain-body is activated, know that what you are feeling is the pain-body in you. This knowing is all that is needed to break your identification with it. And when identification with it ceases, the transmutation begins. The knowing prevents the old emotion from rising up into your head and taking over not only only the internal dialogue, but also your actions as well as interactions with other people, This means the pain-body cannot use you anymore and re-new itself through you. The old emotion may then still live in you for a while and come up periodically. It may also still occasionally trick you into identifying with it again and thus obscure the knowing, but not for long. Not projecting the old emotion into situations means facing it directly within yourself. It may not be pleasant, but it won't kill you. Your Presence is more than capable of containing it."

From A New Earth, by Eckhart Tolle.

This is beautiful.