I use an ultrasonic cleaner with hot soapy water on my molds before shipping, but the ones I make for myself I don't even bother with that.
For myself, I blow dry the mold with compressed air when I remove it from the lathe and just cast with it. IF the new mold gives me trouble, I crank up the heat for a few minutes, see smoke, and drop the temperature back down.
So, my cleaning/break in recommendation is to do nothing but cast. On the rare occasion of fill-out trouble, smoke it. (That's easier than explaining my hot casting solve)