3 weeks ultrasound
Scans in early pregnancy are usually performed in the first trimester around 12 weeks. You may have a earlier scan, if you are experiencing pain or bleeding for example or unsure of LMP dates.
At 2 weeks you are ovulating and you won't get a positive pregnancy until near 4 weeks cause the first week of pregnancy is actually starting your period so you are not actually pregnant until after 3 weeks when the baby implants.
Its pretty early to do an ultrasound, I don't think that even transvaginal ultrasound will catch 3 weeks pregnancy=1 week fetus