One of the most common themes in the pedagogy of photography is that it simply takes time and experience to learn to take pictures. The single most common theme, of course, is "take my workshop" so this is probably the second most common theme. We see Cartier-Bresson quoted ad nauseum to the effect that your first 10,000 photographs are your worst. We see blog posts chattering away about how there is no royal road to great pictures, and so forth. I've even written some of them. Implicit in all of these is that you can expect to be terrible for years and years and years, but keep at it, and you'll eventually become good.
Unpacking that a little, we find the planted axiom that very little about photography is teachable. You simply have to go work it all out on your own, except for a few technical things here and there which are themselves quite difficult to master.
There is, of course, a germ of truth hiding in here someplace, but most of it is complete rot.
You can learn calculus of one variable in two semesters, while taking other courses at the same time. You can learn to speak a language passably in two years, if you apply yourself. Mastering the camera is, relatively, trivial.
You can learn the details of exposure and which controls do what with about 50 well designed exposures in a decently designed program of education. It might take you an afternoon to fully grasp how your camera works, and what shutter speed, aperture, and ISO do. It will, of course, take some more time to internalize these things.
You can surely learn the basics of composition, at least enough to have a working grasp of some useful ideas, in a couple of weeks and a couple hundred more well managed exposures. I have written a handy little book based on this idea. There's an endless supply of material to learn about composition, both general ideas, as well as the specifics of certain idioms. Still, a basic toolkit of composition is short and easy to master. Again, of course, the problem of internalizing it rears its head. As an aside: here, specifically, we have a problem with masses of misinformation out there, which can really confuse the newcomer and slow forward progress.
You can learn the basics of photographic lighting in a couple of afternoons, if that sort of thing interests you. Again, there are endless permutations and idioms to learn, but a basic toolkit is compact and easy to grasp. The same issues of internalizing it apply, of course.
In short, the material you need to know to take a pretty good picture pretty consistently is maybe a month or two of work. You're not a great artist at this point, but you can take a reasonable picture much of them time, and you can recognize good ones most of the time and even explain why they're good. In fact, anyone can recognize the good ones, that's sort of the point of "good" after all, so what's important is the ability to explain why they're good.
Of course all this assumes that you're in the hands of someone who's good at teaching, and who isn't invested in the ideas that this material is years and years of labor, that it's very hard, and that you have to figure it all out yourself. It might reasonably take you more than a month or two to figure things out, but I think it is reasonable to say that if you have been applying yourself at least a little for a year, and still cannot take a properly exposed picture with the focus in the right place and which is pleasing to the eye, except by accident, something in the pedagogical process has gone horribly wrong.
The germ of truth, and what Cartier-Bresson was surely talking about, is that having mastered these technical issues you are now faced with the problem of internalizing this material, letting it become second nature to you, and of simultaneously finding your own vision and voice. These things go hand in hand. You need to discover what you like to look at, what you like to make, how to make that stuff, and how to make it without laboriously thinking through what aperture does to a picture.
This is not merely a years long process, this is a journey without end. It is arguably a lot of time to get from simply making copies of things you've seen to making things that look like your pictures. Some people get there remarkably fast, others never get there.
Still, this is the fun part. You're done with the "education" when you can take a nice picture with the exposure and focus and focal length that you want. Now you're discovering your art. Now you're "working" and not "learning" in some reasonable sense.