Welcome!
Welcome to the board! You're going to love having a Cavalier. They're even more beautiful as adults as they are as puppies! All around, they're the perfect breed. :lotsaluv:
My Blenheim, Jasper, is 12 months old now and has always had a fairly thin, silky coat. I'm not sure, but maybe this is an individual characteristic...? I've seen Cavs with very thick coats and some with thinner, silkier coats. Jasper's is definitely silkier. He didn't get any of the pretty feathering until he was 8 months old, I'd guess, and now it's coming in very nicely. The hair on his ears is finally getting longer, too. His chest hair is starting to fill out and get a bit curlier, but the hair on his back is still only an inch or so long. I don't think he's reached his full adult size yet. Cavaliers take a bit longer to readh adulthood than other breeds do. Maybe 18 months-2 years, if I'm not mistaken.
My first Cavalier was a male tricolor, and I swear he didn't seem to get his full coat until he was over 2 years old! Actually, he may have even been around 3 when I noticed his coat getting thicker and curlier. Somehow it just kept filling out after he reached adulthood. I don't know whether to expect the same thing from Jasper or not.
Anyway, congratulations on your little puppy, and welcome to the forum! I'm relatively new myself, and the people here have been incredibly helpful and supportive.
Lori