Love, it is NEVER to early to start next years costume.
I'm not anything doll like this year (in fact, i'm a big colorful, loud, squawking bird that needs to hand sew 3500 feathers onto a dress she still needs to make)
But I have been a china doll in the past, I wore an old southern belle dress my aunt used to have, and I had an old parasol I painted, nad a bonnet I fixed, and it was awsome. I di paint my face stark white and have rouge blush and scarlet red lips.
I can't really reccoment costume ideas, but you can (I have done this before) take injry makeup, and make it appear that you are cracked china, or part of your cheek and neck are, you just take tissue, and liquid latex and lay it in spaces where it appears cracked, and you can spray it over with hairspray to harden it and give it that china look. <3