The old recommendation was a first oil change after initial breakin, in other words at 10 hours. The owners manual that came with my machine says 50 hours or one year. No way 100 hours on first change.
Manufacturers of almost all engines (boats, motorcycles, cars, pwc, etc.) used to say the MOST important oil change was the first one that was always specified after the breakin period. Some say it's no longer necessary due to "improved machining techniques". Sorry, I don't believe that. I say the biggest reason for extended oil change intervals is due to the epa and the goverment making vehicles reduce their carbon footprint and reducing waste oil is an easy way to do that. I'm doingmine at 10 hours.