If you must use fitness balls for your baby, it is recommended to use them after 6 to 8 months. At that time, your baby's muscle strength has developed to a certain extent, and the brain's control over the body has gradually increased. You can do some balance training to lay the foundation for toddlers in the future.
Whether choosing fitness balls or other babies' toys, the most important thing is to see the materials clearly and choose regular products certified by CCC safety standards. If possible, you can also refer to the safety standards of the European Union and the United States, such as SGS and CE. After all, these standards are stricter than CCC standards.