Okay, double checked. Per Roy's obituary it was August 16th, 1955. You're definitely correct that the timing would be impossible (by 3 months). Unless Sarah lied about his date of birth for some reason.

Do we know the actual date in the current time line (2012 or 1955)? (I don't know that I've been paying that close attention) Average human gestation is 40 weeks. Counting backwards, I got November 25th for conception, give or take a week or two. If the show is following 'real time' that would be pretty close... that…

I just posted a list in the YT comments. Still a few unknowns though.