The answer is based on two important aspects. As far as the baby is concerned, he should be able to hold himself reasonably and control the neck muscles. Usually this developmental phase begins around the age of 4 months. However, the position of the baby on the back is physiologically natural, so from a developmental point of view there is no reason to avoid carrying on the back from birth while maintaining strict carrying safety and tying quality.
If the first few times your baby is not enthusiastic about back carrying, you can place her on your back in front of a mirror so she can see herself and have fun with you. At the beginning, you may also want to play an airplane game, put the baby on the back without the carrier. And of course, dance, move, sings and jump together.