I'm not sure what is meant by drawing from the elbow, I've found it's really drawing from the shoulder mostly. When I teach, we start with the shoulder for gestures and blocking. Then as you get more detailed you use your elbow more then your wrist and fingers (still employing the shoulder). Some of the best use this technique. Search on the web for Mark Westermoe for the final detail techniques; I think you'll enjoy his work.
drawing from the elbow is not for everyone. I draw exclusively "from the wrist" and I turned out just fine. one of my professors years back remarked that I was just "one of those people who can make it work for them"
How long it takes just depends on how quickly/easily you personally pick it up. There's no set time frame for this stuff, honestly. I couldn't tell you how long it took me exactly. I'm pretty sure I picked up the technique my first year in art school. As already mentioned, it's easier to do if you're working larger. Not something I focus on doing small sketches or detail work on a larger piece. But doing a gesture drawing on an 18x24 sheet, it's definitely the way to go.
Oh, ok I'm still learning there isn't a time frame for learning art in general, if you don't mind me asking what did you study in art school? I'm in my first year of high school and I'm already thinking about applying to art colleges and stuff. And what is gesture drawing???
Well, you're way ahead of me when I was a freshman in high school.
I majored in printmaking in art school, but my school had a first year foundation program, so you didn't start your studio program until 2nd year. Foundation programs differ in structure from school to school, but they typically include some kind of life drawing component. And that was the main focus of my 1st semester for the first month or so. I also took a figure drawing workshop my 2nd semester. I was also required to take a certain number of credit hours of drawing classes for my studio program.
A gesture drawing is a very quick drawing, usually under 2 minutes, where you just focus on the pose or gesture of the figure. They're often used as an exercise to loosen your up, and it's easier to loosen up when you use your whole arm, rather than working from the wrist. How you hold your tool also makes a difference.
Well, with me it was a bit weird - when I was yonger, I could not fathom how you can draw from your elbow, but then I was not iterested in art anyway. Once I decided to do art, I kind of got the hand of a few things at the same time alsmost right away. I don't know how to described - some combination of being really focused bout the task at hand and it just 'clicking' in how you think about it. But yes, practise makes perfect. Just think you have to get it done.