I usually get comments within the first week. I carry a lot of weight in my face, and always get asked by friends if i've bought a new eye shaddow. I, strangely enough, notice that the weight first comes off from my eyelids. Weird, i know! But usually within a week or so of starting a diet, I have more space on my eyelids to put eye shadow so people think it's something new! Weird.
My mum is very 'anti fat people' and has been all her life - she's a twig and is forever bragging over it. So she notices straight away when I lose weight, but never in a complementary way, always in a "see that wasn't so hard, why couldn't you have lost the weight ages ago, you could be so pretty...".
Argh!