I don't think a couple of drinks in very early stages will do much harm, the first few weeks bubs is surviving off the yolk sac before it attaches with the ubilical cord and has access to your blood supply.

I found out I was pregnant after being away on holiday relaxing with more than just couple red wines a few of the nights away & had the major guilts but was reassured by doc that all was ok.

As the others have said moderation is the key and do what you feel comforable with.