The earlier the better. While you tell her, be sure to reinforce how badly you wanted to have her and how lucky you felt having adopted her. And that it is she who completed your life. Some people feel that it’s better to wait until the child is an adult because small children cannot handle such a complex reality. But please understand that while you feel protective about your child, the outside world is not the same and someone may say it by mistake or to deliberately cause hurt. And then you will be left with a bigger problem to handle. To evaluate your child’s maturity level, your social/ family situation, and decide when is the right time.