Your Owners manual should have that for you, For my Kawasaki FRX651, the OM states to do 1st oil change @ 8 hours to get the break-in oil out. After my book says 200 hours, but I only put on 25 hours per season, so I change oil & filter end of each mow season. So after over 4 + years of ownership I'm only at 110 hours.
I'm with you. My old mower just finished its 12th season and has 233 hours on it, which is about 20 hrs/yr. Here's what the docs for Huster/Kawi say:
Kawi FR691V printed OM: Change the oil every 100 hours and the filter every 200 hours. For me that's every five years for the oil and 10 years for the filter (yeah, sure). There's no mention of an early first oil change.
Kawi FR691V PDF manual: Same as above except specifies the initial oil and filter change to be at eight hours.
Raptor printed OM: Initial oil and filter change at five hours, then "per the engine manufacturer's recommendations" thereafter.
Raptor PDF OM: Initial oil change at five hours (no mention of filter), then every 40 hours thereafter. For the oil filter it says "per the engine manufacturer's recommendations."
This doesn't exactly jibe, now does it. Nonetheless, I'll be doing my first oil and filter change at five hours, then every year (~20 hours) thereafter.