The Exodus happened 1446 B.C. (for instance, see Rodger Young website rcyoung.org; or book by "From Abraham to Paul - a biblical chronology" by Andrew Steinmann; or "Kingdom of Priests" by Eugene Merrill).
430 years before that was the second year of the famine in Egypt (Exodus 12:40-41), when Jacob was 130 years old (Genesis 47:9). Jacob entered 14th Nisan 1876 B.C.
Isaac was 60 years old when Jacob was born (Gen 25:26).
Abraham was 100 when Isaac was born (Gen 21:5). Finally Abraham is called to leave Haran when he was 75 years old (Gen 12:4); and Ishmael was born when Abraham was 86 years old (Gen 16:16).
2166 Abraham born (Gen 21:5)
2091 God calls Abraham to leave his kindred (Gen 12:4)
2080 Ishmael born (Gen 16:16)
2066 Isaac born (Gen 25:26)
2006 Jacob born (Gen 47:9)
1876 Jacob enters Egypt (Exodus 12:40-41).
There is no date given for the vision of Genesis 15. We do know he was between 75 and 86 years old. It also looks as if Genesis 12 to Genesis 15 gives a chronological order, which suggests many years have passed since his call to leave Haran.
Supposing he was 82 plus or minus 3 years then the time to Jacob's descent into Egypt was 208 years plus or minus 3 years.
All of these dates suppose that each patriarch was exactly such and such an age. If we want to be slightly closer, I guess we should add 6 months on average to each birth year date for Abraham, Isaac, and Jacob, which would mean Abraham was more likely born 2168 B.C., and thus the descent into Egypt was 210 years plus or minus 3 years.