It depends on what version you have. Usually, the baby evolves into a child one hour after it is hatched. After one day, it will turn into a teenager, and after two to three more days it will turn to an adult. This is just a rough guideline...there are many factors that could influence its growth. (Pausing, what version you have...) The Music Star and Tama-Go teens become adults after one day of being a teenager. The other versions usually take longer. Also, mail comes during important times in your Tama's life. (When it can go to preschool, school, work...etc.) The postman can also send you fortunes.