
I don't know Nova as quite a few pups of our breed at 6 - 7 months run bum high I would say most have levelled out by 9 months. There are some lines that rarely seem to do this, but most pups do to some extent at 5 - 6 months.
To the original poster I would say this is likely to be breed and lien specific, so if showing against other pups of the same age they are likely to be similar and a judge will take age into account in puppy classes.