For a beginner coming from trumpet, where the pinky is never used, I think you simply need to build strength and dexterity in your pinky. Rather than make any mechanical changes to the horn at this point, really work that pinky table in every practice session, especially B and Bb which require the most strength. And if you want to continue to build strength between practice sessions, get something like this thing that guitar players use:
https://www.amazon.com/DAddario-Exerciser-Improve-Dexterity-Comfortable-Conditioning/dp/B001OCGGEM
