Yes, it is better to drain early and often. The first drain (at 20-30 mins) will usually have a lot of metal glitter in the oil from parts doing their initial wear-in. It will also help flush out any leftover manufacturing debris. Then change every 5-10 hours depending on the amount of glitter.
After the 30 hours, it should be good to go for the normal oil change interval.
I also added a magnetic dipstick to my generators. Not really needed, but it does pick up some fine ferrous material that's suspended in the oil, so I suppose that's beneficial. I don't have one on my mower and it has been running fine for 17 years. YMMV