Tampons

At what age do you think a girl should start wearing tampons? My little sister started when she was 10 and now 12 and she absolutely hates pads and I started when I was 9 and I know the feeling! Anyways my Nana is raising my 5 younger siblings and she old fashion and sometimes just plain ignorant, she thinks my little sister is going to loose her virginity to a tampon...

My nana is very hard headed so she doesn't listen. I kind of want to explain to my sister what they are and stuff and just hide it from my nana. I had to from my mom when I was 12... I think my sister should use what's comfortable to her. Advice???