Although I sit firmly on the drinking couch for most of the month, I'm definitely not "drink til pink."
After over a year of trying, and one missed m/c, I don't even THINK about non-pregnancy friendly things from about 7dpo on. I have this weird vision of my drunk uterus not knowing what to do with the fertilized egg as it floats on by.....LOL. Same goes for my husband and his sober sperm (during fw).
This is completely non-scientific, and probably a bunch of malarky, but I feel guilty taking any chances. I make up for it with plenty of sushi and wine during the rest of the month :-)
I think as long as you're not getting tanked on the regular the entire 2ww there's nothing to worry about, lol! I do refrain from ib profin and other meds during the 2ww, though.