Lee Child starts a new Jack Reacher novel on the same date every year: September 1. He's kept the ritual for the whole series, sitting down on that day whether or not he has any idea what the book will be about. The date isn't random. It marks the anniversary of when he began his very first novel.

The Direct Answer
September 1. He begins a new Jack Reacher novel on that exact date every year.
He picked it because it's the anniversary of starting his first book, calling it 'kind of sentimental, but it's also common sense,' per Fast Company.

Every September 1

Child publishes one Jack Reacher novel a year, and the writing of each one begins on September 1. He sits down that day with a blank page and, often, no idea what the story will be, then works on it for roughly the next six months. He's said many times that he starts each new book in the series on the anniversary of the day he began the first one. The fixed date gives an otherwise open-ended year a spine. There's a starting gun on September 1, a finished manuscript by late winter, and the rest of the calendar for touring, editing, and everything else that comes with the job. For a writer who plots nothing in advance, that one immovable date does a lot of the organizing that an outline might do for someone else.

Why That Date

The anniversary goes back to the end of his first career. Under his real name, James Dover Grant, he spent about eighteen years at Granada Television in England, until a corporate restructuring cut his job in the mid-1990s. Instead of chasing similar work, he decided to write a novel. The exact date gets told a few slightly different ways across interviews and profiles, but the shape of it stays consistent. Out of a job, he bought a few dollars' worth of paper and pencils and started writing the book that became Killing Floor, published in 1997. September 1 is the date he has attached to that beginning, and he's used it as his annual start line ever since. Every new Reacher book, in a sense, restarts the moment he bet his living on writing.

That was the day I started my first book, so it's kind of sentimental, but it's also common sense.

Lee Child, interview with Fast Company

The common-sense half of that line is about discipline. One book a year needs a deadline, and a fixed calendar date supplies one with no room to negotiate. He tends to write in the afternoons and evenings rather than at dawn, and once the September start pulls him in, the draft carries through the winter. The sentiment and the structure end up reinforcing each other: a date that means something is a date he's far more likely to honor. For his daily hours and the rest of his habits, see the full Lee Child writing routine.

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