It's important to know, that your Bichon Frises coat will change drastically from puppy hood to adulthood. Their baby coat can be curly, straight or wavy. This does not mean that they will have the same hair when they are fully grown. No one can guess what your baby will look like. The look of the parents will help to determine that, but no one can guess how many generations back your babies look will come from. Some straight haired babies develop a lot of curl and some curly babies get straighter hair as adults. Each puppy is different.
When you first get your Bichon baby, she probably had a light fluffy fur coat but at around three to six months of age this will change and she will start to grow in her beautiful soft baby coat.
Your puppy may drop its infant coat from the neck down to the tail and look as if the night elves were taking out her hair one at a time. If you look closely you will see short hair growing in underneath. This new baby hair will continue to grow and get thicker until the puppy is an adult at 3 years of age.
Yes, she will lose her first hair (infant hair) and go through a stage of having a thin, patchy, ugly coat, followed by growing in a thicker adult coat. This can happen anywhere from 3-6 months. Her full adult coat should be in place by 3 years of age. And yes, breeding and bloodlines do determine exactly how full a dog's coat will be. The boy's hair tends to grow in faster than the girls do.
The Bichon coat is unique. The undercoat is soft and dense, the guard hairs coarser and curlier. When trimmed, the coat follows the lines of the body and is left long enough to give the breed's characteristic poufy appearance, with hair left longer on head, ears, beard, and tail. The coat should not be wiry, limp, or over-soft.
A baby Bichon can also have buff, cream, apricot shading. These blushes of color fade during the babies first year until your puppy becomes a white lap mop. Adult with these shadings are heavily penalized.
A Bichon Frises fur is white but their skin will develop black or dark pigment spots. These spots so I have been told tell that they indicate that the dog has very good immunities. I am not a scientist so I can't tell you why.
I do know these black spots are normal and desirable. The skin pigmentation is what breeders try to achieve, and your puppy will eventually look like a piebald all over when bathed. This pigmentation gives the puppy her black lips and halos around her eyes as well as her black button nose.