How Long Does It Take to Achieve B1 in Italian from English?

Hello--I've learned that while I have an Italian grandfather, that I don't qualify for citizenship by descent because he became a US citizen before my mother was an adult, thereby breaking the line. I've been told I could reside in Italy for 2 years and aquire citizenship on a "fast track" because of that ancestry. I'd have to attain a B1 level in Italian. If my wife and I are living in Italy and studying--is it realistic to acheive B1 status in 2 years? I currently only speak English and I speak some Spanish (I can only speak in the present tense but I can understand the gist of most conversations with native Spanish speakers). Thank you!