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:
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 the following table with the year of Abraham's birth in the format (AM, BC) for each combination of the positions on the disputed points, adding 1 to the BC dates in Thiele's chronologies because in each system the sum of the AM and BC dates of any event, including Creation, must be constant:
| short sojourn | long sojourn |
------------+---------------+--------------+
Early birth | (1948, 1952) | (1948, 2167) |
------------+---------------+--------------+
Late birth | (2008, 1952) | (2008, 2167) |
------------+-------------- +--------------+
Note on the short sojourn position
The short sojourn position 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 K_E, Kohath's fathering age (i.e. his age at Amram's birth) as K_FA and Amram's fathering age as A_FA, and since Moses was 80 y.o. at the time of Exodus (Ex 7:7), we have:
Exodus - Entry into Egypt = K_FA - K_E + A_FA + 80
where Kohath's and Amram's begetting ages must be less than their respective lifetimes and K_E must be greater than zero. Thus, a sojourn time of 215 years can be achieved in a number of ways, such as setting the fathering ages at the middle of the respective lifetimes:
For K_E = 1, K_FA = 67 & A_FA = 69, sojourn time = 215 years
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 --- 1 --- .. ---- .. --- .. --- .
30 --- 31 --- .. ---- .. --- .. --- 4
60 --- 61 --- 15 ---- .. --- .. --- 4 x 4 = 16
90 --- 91 --- 45 ---- 24 --- .. --- 16 x 4 = 64
120 --- 121 --- 75 ---- 54 --- .. --- 64 x 4 = 256
150 --- xxx --- 105 ---- 84 --- 15 --- 256 x 4 = 1024
180 --- xxx --- xxx ---- 114 --- 45 --- 1024 x 4 = 4096
210 --- xxx --- xxx ---- xxx --- 75 --- 4096 x 2 = 8192