They have their adult coat around 18 mo to 2 yrs. I have a 2 year 4 mo old and she is staying pretty much the same color. The one thing I have noticed change in the last 6 months is her tan points have become a deeper color (more reddish). I was told by a breeder once that those areas do deepen in color as they age.
And no they may settle some as they mature, but they keep their fiesty and spunky ways. They just get better and better with age.
Telea