This depends on how long it has been since you previously were practicing forgiveness. If you have left the process for a few weeks, I suggest that you start at the beginning. This does not mean that it will take you a long time to get to where you left off. Some of the challenges in the early part of forgiveness (such as uncovering the effects of resentment) likely will be confronted quickly so that you can keep going in the forgiveness process.
For additional information, see The Four Phases of Forgiveness.