The length of time to forgiveness can vary greatly across people and even within any given person, depending on who did the hurting and how deep the anger is. We find that consistent work on forgiveness for about 12 weeks for many people can produce a reduction in anger and a promotion of emotional healing.
This is not a rigid rule at all. Some people require a year of forgiveness work before the anger no longer is in control. A key to keep in mind is this: Even if you have some anger left over, even if you have not perfectly forgiven, you can lead an emotionally-healthy life although some anger remains. Keep working on forgiving, knowing that it is a path to keeping anger under your control rather than the reverse.