What Actually Happens, In Order
Genesis 12:1 to 4. Leave your country, your people and your father's household. The promise is land, a great nation, and blessing for all peoples on earth.
God counts the stars with him and credits his belief as righteousness. Then a covenant ceremony in which God alone passes between the pieces, taking the obligation on Himself.
Ten years in, Sarai proposes a solution and Abram agrees to it. The result is a son, a broken household, and a woman in the wilderness being met by God.
Genesis 17. Abram, exalted father, becomes Abraham, father of many. He is given a new name a full year before he has the son it refers to.
Genesis 21:5. The name means laughter, and both parents had already supplied it. Then Genesis 22, then Sarah's death at 127, then his own at 175.
Read the chapter headings and it looks like a highlight reel. Read the ages and it is a man being given a promise and then living a quarter of a century without it.