Why does Tristram Shandy begin with Tristram's conception rather than his birth?

In Laurence Sterne's experimental novel Tristram Shandy, the narrator begins his life story at the moment of his conception to illustrate the circumstances he believes shaped his character. Specifically, he recounts how an innocent remark by his mother distracted his father at the critical moment, which Tristram believes resulted in him being conceived as a "weakling".12

By starting at this point, Tristram initiates a complex narrative structure that allows him to explore the Lockean principle of the association of ideas. To fully explain his own existence, he finds it necessary to digress into the details of his parents' marriage, his family environment, and the eccentricities of characters like his Uncle Toby. This approach highlights the novel's central themes regarding the limitations of language, the nature of human isolation, and the discrepancy between clock time and lived experience, ultimately leading to the realization that it takes more time to tell the story of a life than it does to live it.12