Congrats!! I'm 33 weeks now and have had excellent care here. My doctor is Dr. German Romiglio who works exclusively with the cuerpo medical de Otamendi (can't think of English!!). I was a little skeptical at first because he's very by the book and was a little cold, but after months with him he's really been awesome and has warmed up a lot. He doesn't speak english though so my fiancee is always there at all of the apts so that we understand everything that's going on. He works with a great team of birthing coaches that give classes and assist during the birth.
Here are a few suggestions. If you're going to have your baby at a private hospital, you'll have to reserve a room by 12 weeks. You'll need to find out where your doctor delivers and have him write give you a prescription sheet stating the date so that you can reserve your room.
If you are working, you should let your employer know after two months, but definitely before you hit 3 months. I guess this depends on your working situation and your relationship, but as you'll be needing time for apts, definitely let them know. My company has been amazing and super supportive of everything. They need to see the note from your doctor to verify things.
Also, have your doctor write another note to give to your medical insurance so that you can immediately be put on the Plan Maternal y Infantil. For most medical insurances this means that your vitamins and any shots necessary are free.
If you have any questions, just let me know!