With respect, I cannot concur with the notion that a soul exchange has to happen at the time of birth.
In my view, the waiting soul imprints its frequency at the moment of conception, thus reserving the right to occupy the zygote even before it develops.  During this process the soul is not confined to the fetus and may come and go as it pleases up until the time of birth.
In my own situation, my immediate past life recall is one of being deliberately euthanized as a newborn by being held so tightly by a big woman, ( wearing a garment with a colorful floral pattern on a black background ) that I was unable to draw breath.  My birth mother may not have been aware that I was born alive.
Possibly for this reason I avoided the birth trauma and exchanged with the former soul in charge of my current form at about its 4th or fifth year through a drowning incident which I recall clearly and which was independently confirmed through kinesiology without my specific enquiry in that direction.

It also seems to me that the prior entity in this body has not entirely vacated but has merely taken a "back seat" and left control up to me. If this is the case, it could explain why, in a disturbing out of body experience, I could witness my body grovelling around on all fours screaming. Somebody was still very evidently home - but it wasn't me.