It is not critical now, its up to you.. It is true the first oil
change should be sooner but you said a few short times run, if that is
under say 6 hrs. leave it and change in the spring, first thing. Acids
have not developed yet . Or change it now if apx 4-6 hrs are on it,
use Mobil Synthetic it is proven to double engine life or more
{ by B.M.W ]

You have no oil filter so take care, that motor is likely rated at 350
- 500 hrs. Pressure oiled motors used in any commercial mower run
2-3000 hrs. at 3600 rpm, and 8-12000 hrs. at 1800 rpm, so keep RPMs
down sharpen blade when dull and use synthetic oil.

Remember 1/2 rpm = 4x life