I had a dating scan at 6ish weeks (I wasn't 100% sure of my cycle length considering I was recently off the pill AND I'd had a miscarriage a couple of months before at 6 weeks so was desperate to know that everything was 'ok' this time), then my ob let me have a quick 'look' at an appointment at 9ish weeks. I then had the scan at 12 weeks to check for downs and my 20 week scan.