Words of wisdom.
Also, cross-reference this with hluska's comment about his grandma:
> As far as how it felt, my Grandma always smiled when she was playing music...
> ...
> So just go out there and fiddle with your instrument and play along to stuff you like!
yes. that.
what does it "feel like" ? doesn't "feel like" much of anything. For me it's just a _lack_ of hunting around for the right note.
it's like the difference between learning to ride a bicycle and _knowing_ how to ride a bicycle. Knowing doesn't "feel" like much. you just get on and ride. Learning requires effort and concentration. Once you know ... you just do it and don't think about it.
The best way I can describe the limitation is that it's like knowing the shapes of the bottles for the ingredients to a recipe, but you don't know the names or the "why" of how it all works. You can't talk to other musicians about music and you can find yourself doodling the same old songs and patterns over and over. It is harder to get out of your box I feel.
I was in a band in college and I could never play along with the properly trained. "Can you play that in a C minor pentatonic scale?"
"Yeah!... So what frets are those?"
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. :-)
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.
It's a lot of screwing up, starting the song over, and trying again until it sounds right. I started doing this about 20 years ago so I've had quite a bit of practice, but at this point it's really a great feeling to listen to a song on YouTube and know pretty much before I pick up the guitar whether I'm capable of playing it within an hour or so.
It just takes practice. Lots of it. Lots of trial and error. Lots of screw ups. And just embracing/loving the process.
Actually the last part is the most important, because I love playing the guitar. I love music. I play 5 different instruments and music is a deeply important part of my life. My desire to play along to the songs I love trumps wanting to learn it in a more traditional fashion. I could have taken guitar lessons or gotten a teacher to learn proper theory and all of that. But all of that stuff just got in the way of what I wanted to do: play the music I love. Now.
So just go out there and fiddle with your instrument and play along to stuff you like!