^ I'd say Hex first since your planning to wear her sooner. ^_^
Actually if you have the budget Arda's back parted wig like the Chibi or Leia are great starting point KakeraのTsuki.
I got the Leia for my Kongiku wig because at the time the Jasmine wasn't an option and I need a wig that I could start with having long hair for the side loop. It was more work then was need for my purposes since i had to remove most of the back part anyways and sew in in a tone of wefts (3 long ponytails worth) to fill it out again. In doing so I also expanded the wig base too fit my head better.
If you want the part wig recommend the Chibi as their is minimal alteration. My head was too larger still for the Chibi when I ordered one for Mami initially at it is a 22.5" wig in circumference the expands only 1/2 of a inch.
HareyuNanami seeing some in person might change your mind. Some times I know it's cheaper to buy them then make one so I've commissioned three so far. There usually the simpler ones I don't mind farming out.