I did not imply that the baby does not have a blood flow, but either way, I'm not debating this any more. I've been told that there is little-to-no transfer of nutrients between mother's blood and fetus' blood in the first couple of weeks. Something to this effect was mentioned in one of my university lectures last week, in fact. Does the fetus get nutrients before that time? Obviously.
For the first couple of days between fertilizations and implantation, the embryo receives all of its nutrients from what was contained in the egg. Implantation takes up to 2 weeks. During this time yes, there must be some transfer of nutrients and waste, but it is not nearly to the level of a full placenta. Up until a full placenta is formed (~3 weeks), the biggest factor in nutrients for the embryo is that which was contained in the egg.
All of this being said, I'm done with this conversation. If you feel you're putting your pregnancy at risk by drinking a little before you know you're pregnant, then don't do it. My point in my original reply was that there is not a significant enough transfer directly from the mother's blood (nutrients absorbed within the last couple of hours) that a single drink around the time of conception is going to cause deformities or developmental setbacks in your child, so if I happen to decide to have a single cooler a the cabin one weekend and then find out the next weekend that I'm pregnant, I'm not going to freak out. (For what it's worth, I have not yet chosen to have a single sip of alcohol since stopping my BCP, but I'm not much of a drinker anyway.)