... can you tell or see if a puppy has a bad tailset? Is it as soon as the puppy gets up on all four and starts moving around or earlier/later?
TIA

You can see tail set from the get-go. Tail carriage shows up later.

Please explain the difference between tail carriage and tail set. Thank You.

Tail set is where the tail comes off the back/croup. In other words, the extension of the spine.

Tail carriage is the way the tail is carried when the dog moves. Some dogs' tails are carried straight off the back; some are carried "gaily", that is a slight curl upward (and sometimes without the curl, just at an angle above the back; and some are carried curled over the back (similar to some hounds).

Some good examples are shown in the LRC, Inc. Illustrated Standard. Page 19 shows a great example of tail set and carriage. Unfortunately, they got only two out of 3 examples correct on page 13. They show a correct tail set and a low tail set, but their example of a high tail set is actually a picture of tail carriage. If the photo of a high tail set showed the tail coming off the back higher than the back (that is, the base of the tail where it leaves the back), that would have been a better example. You can actually feel the bump of a high tail set on a dog.

Ok thanks.... even as early as 3 weeks?