Dickens kept office hours for a man who never went to an office. He sat down around nine, worked until two in near-total silence, then spent the afternoon walking it off.

The Direct Answer
He wrote from roughly 9am to 2pm, then walked a dozen or more miles.
His son recalled that no city clerk kept hours more methodical, as quoted in Mason Currey's Daily Rituals.

Five Hours, Same Hours, Every Day

Dickens rose at seven, breakfasted at eight, and was at his desk by nine. He stayed there until two o'clock whether the words came or not. His eldest son, Charley, said no city clerk was ever more methodical or orderly than his father, and that Dickens discharged imaginative work with the regularity of a man balancing ledgers. The schedule barely moved across the years. Nine to two was the spine of the day, and everything else, the meals, the letters, the family, got arranged around it.

The quiet was non-negotiable. At Tavistock House in London he had an extra door fitted to the study to muffle the noise of the household, and the family understood that the closed door meant silence in that part of the house. He wrote by hand, on one side of the paper, calling each finished page a slip. A good morning brought around two thousand words. On a thin one he stayed put anyway, doodling and staring and waiting, refusing to leave the chair early because the leaving, not the dryness, was what broke the habit.

Output was steady rather than frantic. Two to four slips a day, repeated for decades, is how one man produced Oliver Twist, David Copperfield, Bleak House, and the rest. The lesson hiding inside the dullness of it is that the consistency did the heavy lifting, not any single heroic burst at the desk.

Lunch fit the same machinery. He came to the family table at two, ate quickly, and often barely spoke, his head still half inside the morning's work before he changed gears for the afternoon. The hours were so fixed that the people around him organized their own days against the rhythm of his closed study door.

Then He Walked

At two o'clock he stopped and went out. The afternoon walk ran three hours or more, often around twelve miles, sometimes far longer, through the streets of London or across the Kent countryside near his house at Gad's Hill. He treated it as part of the work, not a break from it. His eyes roved as he went, collecting faces, signboards, gestures, and overheard scraps that surfaced later in the novels. Biographer Peter Ackroyd reckoned he could cover those twelve miles in roughly two and a half hours, which is a brisk clip for a man supposedly relaxing.

The night walks were the extreme version. When insomnia kept him up, or when a book had its hooks in him, he prowled the dark city for hours, and he was proud enough of the distances to put them in his letters.

Thinking whereof, he walked about the black streets of London, fifteen and twenty miles, many a night when all the sober folks had gone to bed.

Charles Dickens on writing A Christmas Carol, letter to Cornelius Felton, 2 January 1844

The morning desk and the afternoon road fed each other. He sat to write, then he walked to refill, then he sat again the next day. For the full picture of how the two halves fit together, see the full Charles Dickens writing routine.

What You Can Steal