Personhood

This discussion that came up in a discussion group I'm in, and so I thought I'd post here as well. The issue deals with when a person becomes a person in general. What we have kinda concluded there is that when a human is embodied with a soul from/by God, then it becomes a person. Or: body + soul = person. Being Christians, we also all agreed that God is the one implants the soul into the body (indicated by the 'from/by' above). Two questions then emerge:

1) When does this take place?
2) Does this always happen? (This was my own question.)

There have been several issues at stake with (1). One lady has posted Psalm 51:5 and Jer 1:5 as precedence for personhood beginning at conception. Those texts:

Psa. 51:5 (KJV) Behold, I was shapen in iniquity; and in sin did my mother conceive me.
Jer. 1:5 (WEB) Before I formed you in the belly I knew you, and before you came forth out of the womb I sanctified you...

I then replied that these are great precedents, but logically, precedents can (and do) get broken. Which brought another question:

1b) Does God follow the same precedent every time?

So before I give all my thoughts, I'll let a few people chime in.