Dated circa 1879 I believe this is currently the earliest photo currently known that shows a man (officer) wearing a wristwatch.
It is circa 1879 and is of British officers of the Guides Infantry, 2nd Afghan War (1878-1880), therefore circa 1879.
I have the privilege of believing in having found and sharing, what I believe to be the earliest photo of a man (officer) wearing a watch on his wrist.
Acknowledgements: Copyright: "Courtesy of the Council,National Army Museum, London"
Photograph by John Burke, 2nd Afghan War (1878-1880), circa 1879
Prior to this Bobbee posted this early and great photo dated 1888. It's dated 1888 1st Brigade of the Hazara Field Force, commanded by Colonel Sym of 5th Gurkhas.1888.
Acknowledgements: Copyright: National Army Museum.
Bobbee - WUS
Here is slightly later, 1893, but I can not 100% confirm if officer bottom left (right hand) is definitely wearing a wristwatch, it's
dated 1893 of General Sir Henry Evelyn Wood, V.C., Headquarters Staff & Foreign Observers, Manoeuvres 1893.
This my fourth find from 1894, where we can 100% confirm a wristwatch it's dated 1894 of Colonel Henry Hallam Parr, mounted on his horse The Rajah, India, 1894.
I have now looked at some 30,000 photos, and gathered some 200 (owning 25%) with wristwatches prior to 1918.
But these are the earliest, I believe are 100% attributed by date and provenance