Before you go to bed is the best time to keep a chesbon hanefesh.
Mrs. Sara Yoheved Rigler says that you chesbon hanefesh should validate you rather than depress. So she says for every wrong thing you did that day think of 4 good things you did. Yes, even those you are expected to do, still it is a big deal! When there are those things which are black and white wrong look at where this is coming from. Dont beat yourself up about it. Give yourself an alotted charatah time and after that no more! This is a productive way to end your day.