I am only responding to the original poster's question of according to the Christian Bible, when does a person receive a soul?
First, I'm sorry that it will not be a quick, yes, no, maybe, this is my opinion, because you asked what the Bible teaches about the subject and in order to answer that question, I have to lay down some basic understanding.
I also need to establish the fact that a lot of people who are "Christian" have a mental consent but are still not spiritually awake. Meaning that maybe their beliefs are based in traditions or politics, but the "*Christianity" of the early followers of Christ was based in a spiritual awakening, an experience that resulted in dead being raised, sick being healed and all manner of miraculous things that defy the understanding of the natural mind. Also, please realize that from a Biblical standpoint, a soul and a spirit are not the same thing. Many people don't know that the Bible teaches a plain distinction, but it does. I have a mountain of scriptual references to back up the things I'm going to say, but I lack the time to present it all and I doubt you'd want to read it all...although you might, because I really don't know you.
Now, to the answer:
According to the Bible, a human being is a three part being.
The Bible teaches that a person is a spirit who lives in a body and has a soul. When the spirit enters the body, the proverbial light comes on and the result is a soul or mental construct of self. Hence, the soul is a result of the spirit uniting with a body. When a body begins to form inside a mother, it doesn't belong to the mother, it belongs to the new spirit that takes up residence in it. The union of this body and spirit produces a soul. The spirit is the part of a person that is the real person, the part that lives forever.
So we could say the following:
Spirit--is the dimension of a person that deals with the spirit realm, the part that knows God. A person's spirit can be awake and alert or it can be in a state of zombilikeness where it provides the "electral" sparks to keep the body alive but never gets listened to or heeded. It is comatose in some people.
Soul--this is the part of a person which deals with the mental realm or self-awareness in the physical world. It's the emotional realm, the thought realm, sensibilities, reasoning and thinking. The soul can either guide the spirit if the spirit is comatose or it can be guided by the spirit if the spirit is awake. The soul is affected by emotions and human reasoning. The spirit is not. Our soul is a battlefield and the prize is our spirit. Everyone of us, according to the Bible, has a spirit and that spirit in each of us is either in bondage [a slave to someone or something else] or it is free. A free spirit isn't the same as a hard head or an arrogant attitude. Those things are deceptions of ego and are not spiritual in nature. The soul, or mind and emotions of a person, cannot figure out or rationalize the things of the spirit. The door to a living spirit can only be opened by a conscious choice to believe. Faith is the key. I am getting side-tracked, but it's all tied together.
Body--the physical vessel that houses the spirit, the union of which produces a soul.
In the book of Jeremiah, chapter 1, verse 5, God says to him that he knew him BEFORE he formed him in his mother's womb. This scripture indicates that Jeremiah existed before coming to inhabit a human body. God knew him as a spirit being but when Jeremiah went to inhabit a body, he became a soulish being as well, meaning he obtained awareness of himself in this physical world.
There are other scriptures but I think this one will suffice. I hope I answered your question satisfactorily. "When does the Chirstain Bible teach that a person recieves a soul?"
It teaches that a person is not alive until the spirit inhabits a body and that the spirit comes to inhabit the body while it is still being formed in the mother's womb. It isn't specific on whether that is when the first egg and cell unite but it is certainly there when the heart starts to beat and brain waves start to form, because it is the spirit that gives life and the spirit that causes the electrical spark that makes the heart beat. In the same way, once a spirit leaves a body, the body is dead. The presence of a spirit is life and the absence of a spirit is death, but it is only the body which dies. The spirit continues to live just as it lived before entering the body. The only difference is that the spirit [the person] now carries the soul imprints that it picked up during its life on earth just as we might carry with us the memory of a vacation we took while traveling in a car. Our bodies are like the cars. Our spirits are the real us that are in the car and our soul is the experiences, memories, emotions, thoughts, etc., that we picked up on our trip. Hope I helped and hope I made sense.
*early followers of Jesus never called themselves Christians. They simply referred to their beliefs as "The Way." [yes, it is the same character in the Chinese Bible that is used for Tao. Jesus told his followers, "I am The Way...." He taught them that if they truly wanted to know The Way, then they should know him.] A lot of people don't know that the God of ancient China was the same God as the one the ancient Jews worsipped and that the belief in this God predates Bhuddism and Taoism by as much as 2,500 years. The entire story of the book of Genisis is actually hidden in many writing characters of the Chinese language. I know...that's another subject, but it's interesting. The Bible says that the followers of the Way were first called Christians at Antioch because some people there said they were "little Christs" going around healing the sick and raising the dead and teaching the words of Jesus. Therefore, those people made fun of them and called them Christians which literally meant, "little Christs".