Looks good, the Nano S isn't a particularly small ITX case though so if you want to go smaller then something like a Node 304 would be good. If you don't mind the size though then the Nano S is fine.
Nano S supports bigger CPU coolers (up to 160mm) so you don't have to go with the smaller NH-C12P, but 160mm is still very very tight for most tower coolers. NH-C12P performs well anyway so eh.
Also Nano S only supports up to 160 mm PSUs and the GQ650 is 165mm. Whether or not that'll really make a diference I don't know, but they also recommend even shorter than 160mm for cable management. Perhaps something like this might suit you better (140mm, 650w, 80+ gold).