sorry, I just realised this has been asked (and answered) before

anywhere up to 12 weeks can a dating scan be done but before 10 weeks and after 8 is the preferred time apparently. i have only had external ones after 7 weeks, but for my first baby i was supposed to be 8 weeks but trhey couldnt see properly so did an internal one, and turned out i was about 6weeks and 3 days along. so sometimes if you are very early, they need to do an internal one, it gives a much clearer picture in those really early days. the internal ones arent that bad anyway.

I had mine done at 7+3, but bub was measured at 6+4.
When i went for my nt scan, the lady was really nice and explained to me that 8-10 weeks is normally best. This is because when it's done earlier, bub is so small that they have to zoom in and the edges can become blurred making getting an accurate reading hard, so they can be out by up to a week, which kind of defeats the purpose of a 'dating' scan because you may not get an accurate date anyway.
By 12 weeks bub was measuring spot on for my dates.

All went well. I was 5 weeks 3 days an he was able to see everything he needed to with out doing internal.

Hello I am first timer to this so not too sure how it works so any advice would be great.

I have an amazing 3yr old boy and two beautiful angels looking down on us which were taken last year

I have just found out a few days ago that I am pregnant about 3-4wks

Thanx