We recommend waiting until the baby is sitting up on his own, as this will make it easier for us to carry him on the back.
It is most common to back carry them when they are walking, although we can do it earlier if our baby asks for it.
Keep in mind that carrying the baby in front allows us to establish visual contact with the baby. On the contrary, in the back carrying position the baby is more entertained, and we can have our hands free to do many daily tasks.
The back carry allows a more comfortable distribution of weight across the carrier's body, so it is the most recommended for carrying large babies for long periods of time.
It is also important to take into account the height of the carrier: if the baby limits our field of vision when we carry him/her in front, it is advisable to carry him/her on the back.