Business owners also meaning tradesmen, artisans, etc.
Pompeii, which was destroyed in 79CE, has thousands of ads written on the walls of the houses. Graffiti advertising the nearest brothel, candidates for elections, prices at the local baths, and upcoming games etc. Things like "Once you stay in Gabinius’ hotel you’ll stay there." And "The gladiatorial troop hired by Aulus Seuthus Certus will fight in Pompeii on May 31.There will also be a wild animal hunt. The awnings will be used." I don't know if these are the oldest known forms of advertising but they're certainly the oldest I've seen.