It's one of those things where I think the warnings come from the consequences of more heavy drinking. I have one drink in the evening fairly often - more than once a week, definitely. I rarely have more than one drink. I usually have it right after putting my baby to bed so that there will be a nice stretch where he doesn't want to eat (if your baby isn't doing that yet, he probably will within a month or two).
Your milk alcohol is = to your blood alcohol. So if I have one glass of wine that is 12% alcohol, my blood alcohol might spike at 0.05%. Non-alcoholic beer is 0.5% alcohol, or 10 x worse than my milk at that point.
I try to minimize my baby's exposure to alcohol, but sometimes a glass of wine or a beer is a great pleasure at the end of a long day.