Thanks for the nice comments. I think I probably worked on this on my own (before I worked on it with a teacher) for about six months, just playing from the beginning and going as far as I could before everything fell apart. I don't think I really got to the finale ("Vivace") for some time and there were a lot of other trouble passages that I hadn't really tried to play just yet. Once I started working on the piece with my teacher, though, I worked through it pretty quickly. At that point, we did go through it from beginning to end, but in my practice schedule I actually spent most of my efforts on the most difficult passages first. So I would work on, say, the introduction for my next lesson only for a couple of days in the week until I had it to a good place, but spend the rest of the week going through the finale or other difficult sections slowly. In total, I think I had been working on the piece for about a year at the time of performance. (I can't say how long I worked on it in lessons because during the time I had been taking lessons with my teacher I worked on a *lot* of other music, so there were many, many other lessons where I wasn't working on the Giuliani while it was still being prepped. I did, however, keep it in my practice schedule all during that time.). By the time I was ready to prepare for performance memorization wasn't all that big of a deal because I had been playing it and studying it for so long. Also I had three lessons just before the performance where I played the piece from beginning to end at least once each lesson without music so I could rehearse playing from memory—that helped a great deal because I had someone there with the music in hand who could say, "Wait. Did you know you're playing a G there instead of the B?" Hope all that helps. It's a challenging piece, but with slow study and methodical consideration of fingerings (in my opinion the most difficult thing about this piece) it is certainly accomplishable.
"In music I think it's very, very dangerous if you start to compare and say, 'This is good, this is not good, this is only one possibility' . . . there are so many possibilities, but what is important is to be open to that." - Pavel Steidl