Puddie has a cotton coat ... so I had him trimmed down to a puppy cut. He stays in that; he looks like a little bear cub.
Bella has a "proper" coat, so she just gets trimmed and shaped, kinda like what they do to MY hair when I go (although I think she gets to the groomer more often than *I* do
).
So, I think the answer depends more on your pup's coat than anything else. But if her ends are split, then they're going to tangle, so it's best to get her trimmed up. "How far" depends on what you want to ultimately achieve.