What is the time lapse between Abraham leaving his home country and Sarah giving birth to Isaac?

At 75 years of age Abraham began to move his household out of Haran to the land of Canaan, where he lived out the remaining hundred years of his life in tents as an alien and migratory resident. (Ge 12:4)

Time passed. They had now been in Canaan for about ten years, yet Sarah continued barren. She therefore proposed to substitute her Egyptian maidservant Hagar so that she might have a child by her. Abraham consented. And so in 1932 B.C.E., when Abraham was 86 years old, Ishmael was born. Ge16:3, 15, 16). Soon after, three materialized angels, whom Abraham received hospitably, promised that Sarah herself would conceive and give birth to a son the coming year. Gen 18:1-15.

At the appointed time, 1918 B.C.E., Isaac, the promised heir, was born when Abraham was 100 years old and Sarah was 90. (Ge 18:16--21:7) So according to Bible chronology Abraham left Canan in 1943 B.C.E. (Before Common Era) at the age of 75 and in time became father to Isaac when he was 100 yrs old in 1918 B.C.E. A period of 25 Yrs from his leaving Haran to the birth of Isaac.