Yes, had scan at 7+3 (and my dates are correct as this is a clomid pregnancy with tracked ovulation) and I only measured 6+5. They weren't concerned at all and discharged me from the fertility clinic and booked my next scan for 12+4.
I've heard that within 5-7 days is fine and fairly normal as it can be difficult to get an accurate measurement depending on their position. I have been worried about it but what will be will be. I'm 10+2 now, I had debated a private scan but that isn't going to change the outcome either way so we are saving the money and will hopefully be putting it towards something cute for the little one!