Yes, conception is the first stage of development of a new human person.
And yes, conception is very very special - but nothing particularly special happens to the DNA.
DNA is just a recipe for how to make useful molecular machines and when and where to make them so that a human being forms and begins to grow.
My little daughter has already mixed up the chromosomes she got from me with the ones she got from my beloved wife to make the unique and new DNA sequence she will contribute to any grandchild she ever gives me. THAT was when the new DNA sequence was formed - several decades before she will ever conceive a child.
My second point is that nothing special HAS TO happen to the DNA at conception in order for conception to be the first stage of development of a new human life; and to be very very special.
I pray your wife has a quick and smooth delivery.
I remember sterilizing every thing when my first came home!
By the time my poor last child came along I was just wiping her binky off on my pants. LOL!