Enough is not a state you arrive at
There is always another diary, another regiment, another dialect of the same county. “Knowing enough” is a horizon that retreats as you walk. Writers who wait for it are often protecting themselves from the sentence, not serving the book. The archive will still be there after you have a chapter. It will be more useful then, because you will know what you are looking for.
A story asks specific questions. How long does the coach take. Can she sign. What does the fever do on the third day. Who is in the room when a will is read. Those questions are finite. A general ambition to understand the Napoleonic Wars is not. Draft toward the finite questions. Let the general reading continue beside the draft, not in front of it as a gate.
Footnotes in the draft, not in your courage
When you hit a hole, mark it and keep the scene moving. A bracket is allowed to be ugly: [weapon], [how a maid addresses her], [tide]. The want does not have to wait for the bracket. Stopping the day’s writing to become an expert in tides is how a novel becomes a research project with a working title.
Once a week, gather the brackets and answer the ones the next scenes depend on. Leave the ornamental ones. You will often find that the plot has walked past a fact you were afraid to invent, and that a plain placeholder did no harm. Fear of inaccuracy is healthy. Obedience to it, before a draft exists, is how books stay unwritten.
Research before a story becomes a lecture
If you research for a year with no one wanting anything, you will accumulate explanations. Explanations want to be used. They will press into the draft as guided tours: the history of the street, the organisation of the household, the causes of the shortage. The reader did not ask for a tour. They asked to watch a person.
Questions that come from a plot are already dramatic. You look up inheritance because someone is about to be cheated, not because inheritance is interesting. The fact arrives with a job. Facts gathered in the abstract arrive as display. This is why the same writer can be accurate and dull, or lightly read and alive. Order is the difference.
A small start counts
You do not need the whole century to write the first scene of the pinch. You need the room, the obstacle, and enough ordinary life not to embarrass yourself. Write that scene this week. The rest of the research can answer to it.
If you have been reading for months and have no pages, the kindest interpretation is that you are still choosing. Choose. A person, a want, a price. Then write badly toward it. Accuracy is a revision pass. It cannot revise a blank page.
Try this
Set a rule for the next ten days: you may research only the brackets you wrote yesterday. Everything else waits. At the end of the ten days, count pages, not sources.