Usually this early it is a vaginal ultrasound because it is easier to see the baby and date the pregnancy.
I'm an OB ultrasound tech. I always do an abdominal and vaginal scan until about 10 weeks (and sometimes after depending on the moms body type and uterus shape) allows us to better see/measure the embryo and heartbeat, as well as better assess your uterus and ovaries. I would definitely expect a transvaginal scan around 7 weeks.