The phrase "early chapters" refers to the beginning or initial sections of a book, story, or any other written work. It indicates the early part of the plot or narrative, where the story is just getting started. Full definition
Early chapters provide context in a theoretical discourse on the causes and consequences of psychological and attachment difficulties for children in care, including a discussion of maltreatment and foster care. (springer.com)
How he responds will be an important early chapter in the campaign for 2019. (macleans.ca)
What are your kids favorite early chapter books and / or super heroes? (pragmaticmom.com)