“About two days” can mean two full days of work, two calendar days including other duties or a guess made before seeing the material. An estimate becomes easier to use when its assumptions travel with the number.
Define what is included
Name the deliverable and the main stages. Does the estimate include review, revisions and waiting for information, or only your drafting time? State that boundary before someone builds a schedule around it.
For a hypothetical report, you might estimate one drafting session and one revision session, provided the data is complete. That is more informative than a single number detached from the work.
Separate effort from elapsed time
A task requiring several hours of effort may span several days because of dependencies or other commitments. Explain both where they matter. Do not quietly assume uninterrupted time if your calendar does not contain it.
If the uncertainty is large, say what you need to inspect before narrowing the estimate. A range can be helpful when it reflects real uncertainty rather than a decorative buffer.
Choose a review point
Agree when you will update the estimate, especially after an initial sample or dependency is resolved. Report a change early with the reason, instead of waiting until the original date has passed.
When estimates collide, use a visible priority discussion. The purpose is to support a practical decision about scope and timing, not to make a rough prediction look more certain than it is.