Whatever age you're comfortable with! If it's the insertion of the tampon you're worried about, it's really not that big of a deal. You can't even feel it when it's inside of you! You just have to remember to take it out 4-8 hours after insertion, otherwise you're at risk for toxic shock syndrome. Putting a tampon in is way easier and less painful after you have sex for the first time, but it might be easier to just do it so you have the experience. Personally, I hate tampons because I don't think they're convenient. But whatever floats your boat, sister.
You can use tampons from your very first menstrual cycle. I didn't start until I was about 23!