I waited till their personalities started to show, around 3-4 weeks, to name mine. I named them 1 at a time, until all 6 were named. I had Nala (Simba's girlfriend from Lion King), Daisy, Riley, Teddy, Leo, and Maya.
I like the theme idea too! My local Humane Society does that. Once they had Ross, Rachel, Joey, Phoebe, and Monica. And a batch named after famous kitty characters, Garfield, Moris, Felix, Simba. I like state and city names too. I have a dog named Georgia, a cat named Savannah. My friend has a female mastif named Alabama that they call "Bama."
Naming babies is fun!