Reading the rulebook once and then teaching as you go is fine, actually
I saw a geek on BGG say you should never teach a game before playing it twice solo, and I think that's gatekeeping nonsense. I've taught Wingspan, Azul, and Quest for El Dorado cold off one read-through at my Tuesday meetup in Toledo, and new folks picked all three up in under 15 minutes because we just started playing and fixed stuff as it came up. Does your group learn better from a full dry run first, or do you just dive in?