Papillons will start to grow their adult hair coat at about 7-8 months of age.
At about 15 months they will make another slight change to get their final look.
It takes quite some time to grow all their beautiful hair coat, especially those ear fringes.So, be patient and don't assume your dog is not getting that nice desired long coat!
The length of the Papillons hair is developed mostly depending on his genes, but also on his food, health, environment, grooming.
If you live in a warm climate, your Papillon will have a little less of a hair coat, than if you live in a cold climate.
Look at his pedigree to evaluate the length of hair coat his parents, grandparents have.
Genes do not "blend" or mingle. If mom is short coated, dad is long coated, then your puppy may get the short coat from mom. (or long coat from dad).