The first 2-3 weeks fatigue set in sooner than it used to. This is good for everybody. But it is even more important for a thin rim mouthpiece. I can feel a certain bit of numbness from the thin rim. However, as I've built better embouchure support etc, this numbness is fading away.
Long tones are really good exercises for a new mouthpiece.
I'm still very pleased with the Pizka mouthpiece. It seems to work well with my King Eroica. My playing has sometimes been good, but often below par. I've been trying hard to practice for close to an hour per day through all this. No actually many things of my horn playing have tremendously improved over the past couple of months.