What are you hoping to get from knowing music theory? It seems like many of the commenters are assuming a specific goal from this (etc being able to more easily understand/memorize what you are supposed to play or being easily able to transpose music). Perhaps that is not your goal. And I would offer that music theory might not be the magic bullet for being able to read music much faster (eg better sight reading).<p>I taught instrument playing to a number of people, and I would say that associating the written note to a logical note and then associating a logical note to finger movements to play can be done with little to no formal music theory. These two things are orthogonal, and at least for younger learners, I find that the former (going from written notes on a score to which tone it is) is the most difficult part. That is, if I were to simply call out the notes in turn, the student could play at a much faster rate than if they had to read it themselves and decide what note it was. I found that mobile apps and websites that present notes to you and ask you what they are, helps tremendously for making this process faster. That is, speeding up the whole process is nothing more than repetitive practice. Once single notes are easily and quickly decoded in the mind, multiple simultaneously notes actually come faster because you decide one note at first and then can figure out the others by looking at the relative distance. Music theory can help here by providing some heuristic shortcuts but honestly, I don't find it is necessary or that helpful.<p>Don't worry, the whole process takes time. I would say that if you were already a competent pianist, but one who struggles with reading scores for sight reading, it would probably take months to years to see satisfactory progress, focusing on sight reading alone. That was consistent with my personal experience as well. I would stay away from trying to transpose music, unless you have absolute pitch, in which case transposing music would be easier than reading it in the first place.