[mikestew]

Yeah, but this ain’t The Matrix where you just pull it up, and now you know kung fu. You still need to practice that Cm pentatonic, or you’re just going to fumble around on the fly. For instance, as an experienced musician, I think to myself, “oh, C pentatonic, flat the third”. Live, on the fly, and I’ll probably play a few natural thirds, but hey, we’re jammin’, who cares?

Back to the original question, almost everything music-related comes down to “practice”. In this case practice discerning intervals between notes (there are mobile apps). Practice scales. Practice scales with interval jumps (first to third to fifth, or whatever). Practice scales starting on (say) the third.

But first and foremost, as already mentioned here, get a teacher. Show them this post. They can set you on the start of your journey. Be forewarned, it will be a multi-year process of consistent practice. Getting in a hurry will be your biggest enemy.

How long does it take, OP asks? Depends on how hard and how well you practice. There probably is some ethereal quality we call “talent” that plays a small part, but if decades of playing music has taught me anything, it is that your level of dedication to the instrument is a larger factor than “talent”. Because the most “talented” musicians I know coincidentally play a lot. :-)

[ehnto]

Talent can only get your foot in the door I feel. You see a lot of talented people pick up a topic, do exceedingly well at the basics then just walk away. It's time, dedication and practice that take you from the clever kid destined for great things to a capable musician/crafstman/artisan/programmer.

There parallels between software and music proficiency are pretty strong in this regard. There is a big difference between a clever person who can learn quickly and an experienced programmer with niche domain knowledge earned over years. In the same way musicianship is more than being able to play an instrument.