i've always found the most noticeable colour change (apart from the head) is if you brush upwards on the back thigh and check the roots...
poppet has been s.b on her back for a fair few months (she's 9 months to) but her head hair is only turning to proper gold now- very slowly!
from the 1st pic on your other thread (prob just the way you are holding her) it does look to me she had started to change a little, but i'm assuming you'd have noticed that...
it could be she is just a late bloomer, but it could be just as possible that she will just stay black&tan...
she looks like a little darlin anyways! swap ya!? lol