I think there’s a slight difference in the feel of each sentence.
“I didn’t go to Italy until I had learned Italian,” means to me that the person didn’t dare travel to Italy until he knew he could speak Italian. Maybe he wanted to and planned to, but he made sure he learned Italian first.
“Until I had learned Italian, I didn’t go to Italy,” sounds to me as if the person became interested in going to Italy after he had learned Italian. Maybe he would have gone there without knowing Italian, but it so happened that he went there after he had learned the language.