I've always heard that six months was a good age.

Since this is your first experience with a female, you need to know that it will take Hermoine longer to recover than your boys. Her's is a much more invasive sir-jury so expect her to be pretty groggy and tired for a couple of days. She'll just want to sleep it off in a quiet spot (I can remember Jan snoozing under a dresser - we put a box with a towel down there for her).