Oh no dude, it's one special day in every month of the year. Go to his cell and next to it is a calendar with certain dates circled, and those are the days you would've had to speak to him in 2011, so you need to cross over to the appropriate days in 2012. So fucking long man. The real way to get it is to fuck around with the date settings on the xbox, disconnect the box itself from the internet, speak to him on what xbox thinks is that day, then save, rinse and repeat...
I may have gotten the thread a little schewed, cause it's really quite achievable, it's just a dumb fucking achievement to have included in an otherwise pretty damn flawless game...