That's a hard one to answer. They are all different, like potato chips!!!!
My AprilLove had a crummy puppy coat and I thought I would always keep her in a puppy cut. So I cut it short from 6 months to a year, then decided to grow it out. It took her until after 3 years old to get her final coloring and her coat texture changed dramatically around that time also (for the better). The growing out part is the hardest (especially around the face if you trim that, which I would never have done if I knew then what i know now, LOL), but once you get the long coat, maintaining is pretty easy, imo.
How old is your sweetie?