Next scan

So I went for a abdominal scan 2 weeks ago today and they couldn’t see anything so they told me to come back a week later which was 1 week ago today and they could see the gestational sac and they have told me to come back again to see if can see the yolk sac or fetal pole, I am wondering when you think it’s best to book my next scan, seeing as it took a week for the gestational sac to become visible on scan would it be the same case for the yolk sac and fetal pole? I really want to book it for this week as I am so anxious