T.R.
Hi A., I'm a bit of a medical sponge, always learning. I hadn't heard of this syndrome before, so I googled around...
The bone abnormalities you mention are called "polyostotic fibrous dysplasia" which is a disease that destroys normal bone & replaces it with fibrous tissue. "poly" means it can/does affect more than one bone, and as you already know, it is very commonly associated with the McCune-Albright syndrome.
The link below is the best site I found for information regarding the onset of symptoms specific to the bones. The source is the Mayo Clinic, which to me has a lot more clout than the blog of one person's anecdotal experience.
It indicates that for persons with "fibrous dysplasia" onset is usually in the teens to 20's, but for more severe cases, & specifically for those people affected with the polyostotic form, onset of symptoms usually occurs by age 10.
http://www.mayoclinic.com/health/fibrous-dysplasia/DS0099...
Additionally, I read in Wikipedia, under McCune-Albright syndrome, that 20-30% of dysplasias within the syndrome are polyostotic, & 2/3 of them develop by age 10.
I also found this site, which goes a bit in-depth regarding the genetic cause & linkage of the syndrome, but also has good reference links towards the end for additional articles & information.
http://ghr.nlm.nih.gov/condition/mccune-albright-syndrome
Keep in mind, also, that this syndrome will have different levels of severity, with some people appearing unaffected or only mildly affected, & others having severe deformities.
I would personally urge you to request a referral to an endocrinologist & a geneticist (perhaps you have a large medical complex nearby that might have doctors in these fields that work together?
I hope this was helpful, & I'll be praying that your next appointment helps bring enlightenment to what is going on. Stay positive, & be strong, as your daughter's advocate. T.