
With my Bassets, a thickening of the flanks was usually apparent from around the 4th - 5th week. Some of mine would be quieter from the off, taking more care of themselves when around the others, while others would be as nuts as ever until their increased girth stopped all that. I usually also noticed the vulva hadn't gone back to the pre-mating look. By 7 weeks, puppies can normally be seen moving around.
I didn't ever do scans, preferring to assume, from a good couple (or just one) of matings to a proven male, that I had a pregnancy, making arrangements for the whelping regardless. I realise others do this, but with mine, going to the vet was usually stressful which I didn't want to put my pregnant bitches through (to say nothing of a car trip). Also sick dogs visit vets! That could be avoided by having somebody come to the home to scan (I'm told). But I truly never saw the point. What would be, would be. If my bitches went over by more than a couple of days, I had them into my vet for an examination, maybe an x-ray if it was felt necessary, and a shot to get things moving.
Vets make money from doing things like scanning after all! And add to that, a scan only confirms, or not, a pregnancy at the time of the scan. Not that the bitch will carry to term. Scanning is a different matter if the bitch was caught and there's a need to know, to make decisions. If I'd scanned, and was told no, there would still be a lingering 'what if it's incorrect', to the end of the pregnancy LOL.