Does He do it at birth or during our life?
Do we know when He does it?
At this point I would ask that you provide scripture that teaches us God alone causes us to be born again apart from hearing and believing the Gospel Message of Christ: the incorruptible seed of the word of God.
JLB,
He does so according to, and at a time of, His choosing and good pleasure. Generally, that it has occurred it is made known to us through an ongoing change to our attitudes, perceptions and understanding regarding things spiritual. I do not think this to be just an off/on condition but is continuing and growing within us throughout our lives.
This topic is extremely important, so I definitely understand your concern and desire to fully explore it.
Here are some verses which I think might answer your "ask". Since I'm not completely sure of what you're looking for I'll start with the following. With many of them, we will need to look closely at them and concentrate/ponder what is being said to find their born-again message as it may not always be obvious, plus, context will be important to some of them. Respectfully, please read them very carefully.
There are many, many more so if these don't satisfy your requirement (and I know that I've missed many important ones,) let me know and I'll try to provide others. I would be happy within my limited abilities, to try to clarify any questions you may have.
Also, while probably obvious, let me add that just as we cannot give to themselves human physical life or make ourselves to be born, neither can we give to ourselves spiritual life or make ourselves to be born spiritually. God must do that and from/by which do all other spiritual blessings and gifts flow.
[Jhn 1:13 KJV] 13 Which were
born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
[Jhn 3:3-8 KJV]
3 Jesus answered and said unto him, Verily, verily, I say unto thee,
Except a man be born again, he cannot see the kingdom of God.
4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born?
5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water
and [of] the Spirit, he cannot enter into the kingdom of God.
6 That which is born of the flesh is flesh; and
that which is born of the Spirit is spirit.
7 Marvel not that I said unto thee,
Ye must be born again.
8 The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth:
so is every one that is born of the Spirit.
[Jhn 6:65-66 KJV]
65 And he said, Therefore said I unto you,
that no man can come unto me, except it were given unto him of my Father.
66 From that [time]
many of his disciples went back, and walked no more with him.
[Tit 3:5 KJV] 5 Not by works of righteousness which we have done, but according to his mercy he saved us,
by the washing of regeneration, and renewing of the Holy Ghost;
[Mat 13:15-16 KJV]
15 For this people's heart is waxed gross, and [their] ears are dull of hearing, and their eyes they have closed; lest at any time they should see with [their] eyes, and hear with [their] ears, and should understand with [their] heart, and should be converted, and I should heal them.
16
But blessed [are] your eyes, for they see: and your ears, for they hear.
[Rom 12:2 KJV] 2 And be not conformed to this world: but
be ye transformed by the renewing of your mind, that ye may prove what [is] that good, and acceptable, and perfect, will of God.
[1Co 2:10-14 KJV] 1
10 But God hath revealed [them] unto
us by his Spirit: for the Spirit searcheth all things, yea, the deep things of God.
11 For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God.
12 Now we have received, not the spirit of the world, but the
spirit which is of God; that we might know the things that are freely given to us of God.
13 Which things also we speak,
not in the words which man's wisdom teacheth, but
which the Holy Ghost teacheth; comparing spiritual things with spiritual.
14 But the
natural man receiveth not the things of the Spirit of God: for they are
foolishness unto him: neither can he know [them], because they are spiritually discerned.
[Phl 2:13 KJV] 13 For it is
God which worketh in you both
to will and to do of [his] good pleasure.
[1Pe 1:22-23 KJV]
22 Seeing ye have purified your souls in obeying the truth
through the Spirit unto unfeigned love of the brethren, [see that ye] love one another with a pure heart fervently:
23
Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever.
I'll continue thinking about your question and update the above with more verses that can demonstrate it.