Dating biblical events from Creation and/or from the Christian Era depends on the positions adopted on two disputed points:
The birth of Abraham. There are two positions on the age at which Terah begot Abraham:
- Early birth: Terah was 70 y.o. at Abraham's birth and therefore 145 y.o. at Abraham's departure from Haran.
- Late birth: Terah was 130 y.o. at Abraham's birth and died being 205 y.o. before Abraham's departure from Haran.
The position on this point affects the date from Creation of biblical events from Abraham's birth forward,
and the date from the Christian Era of biblical events previous to Abraham's birth.
The sojourn in Egypt. There are two positions on the time elapsed between Jacob's entry into Egypt and the Exodus:
- Short sojourn: 215 years.
- Long sojourn: 430 years.
The position on this point affects the date from Creation of biblical events following Jacob's entry into Egypt, and the date from the Christian Era of biblical events previous to the Exodus.
Thus, each of the 4 possible combinations of the positions on these disputed points can give a different date for a biblical event, either from Creation, or from the Christian Era, or from both.
In the particular case of Abraham's birth:
the date from Creation (AM, Anno Mundi) depends on the position on his birth; and
the date from the Christian Era (BC, Before Christ) depends on the position on the sojourn in Egypt.
IMHO, a good source for an introduction to the two disputed points and links to further bibliography is:
https://creationwiki.org/Biblical_chronology_dispute
From that source, I made this table with the year of Abraham's birth in the format (AM, BC) for each combination of the positions on the disputed points, according to Thiele's chronology:
| short sojourn | long sojourn |
------------+---------------+--------------+
Early birth | (1948, 1951) | (1948, 2166) |
------------+---------------+--------------+
Late birth | (2008, 1951) | (2008, 2166) |
------------+-------------- +--------------+
Plausible adjustment of the short sojourn position
To note, 215 years is the minimum value for the time in Egypt in the short sojourn position, not the only possible value. This can be easily seen from Paul's statement in Gal 3:17 that the Law came 430 years after God's promise to Abraham and to his offspring. Now, Abraham's act of faith mentioned in Gal 3:6 and God's promise to Abraham and to his offspring mentioned in Gal 3:16 are in Gen 15:6 and 15:18 respectively. Therefore we must estimate the time elapsed between Abraham's departure from Haran (Gen 12:4-5) and the promise in Gen 15:18. If, and only if, both events happened within a few months, so that Abraham was still 75 y.o. at the time of the promise, then the time elapsed from Abraham's birth to the Exodus was:
Abraham's birth - Exodus = 75 + 430 = 505 years
Substracting from that the time elapsed from Abraham's birth to Jacob's entry into Egypt:
Abraham's age at Isaac's birth (Gen 21:5)..: 100
Isaac's age at Jacob's birth (Gen 25:26)...: 060
Jacob's age at entering Egypt (Gen 47:9)...: 130
------------------------------------------------
Abraham's birth to Jacob's entry into Egypt: 290 years
we obtain the minimum short sojourn time: 505 - 290 = 215 years.
However, the Genesis narrative of ch. 12 to 14 clearly fits better with an elapsed time of a few years between Abraham's departure from Haran and the promise in Gen 15:18. Estimating that time as 3 years, then:
Abraham's birth - Exodus = 78 + 430 = 508 years
so that the short sojourn lasted: 508 - 290 = 218 years, and
Abraham's birth = Exodus + 508 = 1446 BC + 508 = 1954 BC
The short sojourn position, both in its usual minimum version or in the adjusted version presented above, fits a literal reading of Moses' genealogy from Levi (Ex 6:16-20), noting that Levi's son Kohath had already been born when Jacob entered Egypt (Gen 46:11). Denoting Kohath's age at the entry into Egypt as KE, Kohath's age at Amram's birth as KBA and Amram's age at Moses' birth as ABM, and knowing that Moses was 80 y.o. at the time of Exodus (Ex 7:7), we have:
Entry into Egypt - Exodus = KBA + ABM - KE + 80
where Kohath's and Amram's begetting ages must be less than their respective lifetimes, and KE must be greater than zero.
KBA + ABM - KE < 133 + 137 = 270
Thus, short sojourn times can be achieved in a number of ways, such as e.g.:
For (KE = 2, KBA = 50, ABM = 90), sojourn time = 218 years [Note 1]
Further observation in the adjusted short sojourn position
If Jesus Christ was born in 7 BC, the time elapsed from Abraham's birth to Jesus's birth: 1954 - 7 = 1947, is the same as the time elapsed from Creation to Abraham's birth in the "early birth" position (1948 - 1 = 1947, as Creation is assigned year # 1 in the chronologies in the linked source.)
[Note 1] This is fully compatible with Num 3:27-28 stating that the number of male descendants of Kohath was 8600, as e.g. in this way:
Years - Age --- Age ----- Age -- Age -- Kohath's
from -- of ---- of ------ of --- of --- patrilineal
entry - Kohath Jochebed Amram Moses male descendants
0 --- 2 --- .. ---- .. --- .. --- .
30 --- 32 --- 12 ---- .. --- .. --- 3
60 --- 62 --- 42 ---- 12 --- .. --- 3 x 5 + 1 = 16
90 --- 92 --- 72 ---- 42 --- .. --- 16 x 5 = 80
120 --- 122 --- 102 ---- 72 --- .. --- 80 x 5 = 400
150 --- xxx --- 132 ---- 102 --- 12 --- 400 x 3 = 1200
180 --- xxx --- xxx ---- 132 --- 42 --- 1200 x 3 = 3600
210 --- xxx --- xxx ---- xxx --- 72 --- 3600 x 2 = 7200