My OB won't see you until 8 weeks, but he's done an internal u/s at my first appt both times. I think its more for dating than anything else. If you do the nuchal fold test you have another between 12-14 weeks. Then at 20 wks. I don't really remember having another after that point.
With your concerns, I'd request to be seen at least prior to the 12 week mark. I'd want to be seen at 8 wks...which seems to be the norm around here for 1st visit.