How old is she, if they want to spay her right away?

A friend of ours fosters mom cat and kittens combos (one mom cat, however many kittens in her litter) for the local animal shelter. The latest bunch of kittens were born before the start of school, and are now back at the shelter awaiting adoption. Of course, our friend P. posts all sorts of adorable photos of them on her FB page, and so far, every time there's been a litter ready for adoption, one or two have ended up with a friend of P.'s thanks to the abundant photographic evidence of extreme cuteness.