The 430 years is from the time of the Abrahamic covenant was established according to Gal 3:16, 17 -
The promises were spoken to Abraham and to his seed. The Scripture
does not say, “and to seeds,” meaning many, but “and to your seed,”
meaning One, who is Christ. What I mean is this: The law that came 430
years later does not revoke the covenant previously established by
God, so as to nullify the promise.
The Abrahamic covenant was first established in Gen 12:1-4 -
Then the LORD said to Abram, “Leave your country, your kindred, and
your father’s household, and go to the land I will show you.
I will make you into a great nation, and I will bless you; I will make
your name great, so that you will be a blessing. I will bless those
who bless you and curse those who curse you; and all the families of
the earth will be blessed through you.”
So Abram departed, as the LORD had directed him, and Lot went with
him. Abram was seventy-five years old when he left Haran.
Note that the passage in Gen 15 and 17 were some years later and so when the covenant promises were repeated to Abraham, the time was correspondingly less, 400 years. In any case, the 400 years is probably a rounded number anyway.
It is also clear that from the time that Jacob moved his family to Egypt until the Exodus was much less that 400 years because it was just the fourth generation (Gen 16:15) we note that:
- There were more than four generations between Abraham and Moses (in fact, there were six generations)
- Four generations does NOT take 400 years
- In fact, it was 215 years between Jacob moving to Egypt and the Exodus under Moses, but this might be the subject of another question.
Thus, the chronological statement are consistent.