Realistic Single-Person Pencil Sketch

I would like a clean, realistic pencil sketch of one person. The subject will be provided through a clear reference photo as soon as we start; no background elements are necessary—just the individual.

I’m aiming for classic graphite work with careful shading and accurate proportions, not a caricature or stylised piece. A high-resolution digital file (JPEG or PNG, 300 dpi) is all I need in the end, though a well-lit photograph of the original page is fine if you’re working traditionally.

Please tell me roughly how long you’ll need, what paper size you prefer, and share a sample or two of similar single-person portraits you’ve completed so I can see your approach before we begin.