You should definitely ask your doctor any questions such as this.
I can tell you that I am 16 weeks pregnant, and didn't know it on New Year's Eve. I didn't drink a lot, but I did have about 2 or 3 mixed drinks. In all 6 of my pregnancies, this has happened prior to knowing that I was pregnant, and in all 6, the doctors always told me that it was O.K, as long as I had stopped! If you continue drinking even after you know, then problems can occur.
As far as taking Tylenol, Acetominophen is the one drug that (in my experience) you ARE allowed to take during pregnancy.
The question of your baby being OK, well, I can't tell you that. Only your doctor can. All I can tell you are MY experiences having children, and what I have been told in the past. If you haven't already had your first appointment, make sure you tell the doctor this.