There is no simple answer to this question. In team sports, the athlete returns to full play or competition when all tasks related to the sport can be done easily, without pain or other symptoms.
Rehabilitation for ankle injuries progresses through a series of exercises. These include range of motion as well as exercises to restore endurance, strength, and power. Usually, the ankle's sense of its own position must be retuned, too.
Check with the coach or trainer about movements that are required for gymnastics. If possible, have a physical therapist evaluate your daughter and design a specific program that will bring her back into gymnastics with less risk of another injury.