My daughter just started her cycle this past month. She is just 11 yrs old. She has been developing in other areas for over 1.5 yrs now. Our doctor was sure that she would have started over a year ago. The general rule is 1-1.5 years after they start to "bud".
As far as the tampon question. We had the same issue arise. The weekend she started, she had the opportunity to go swimming - she really wanted to go, so I call a nurses line to see if there were any medical issues to be concerned about with a YOUNG girl using tampons. There were no "medical" reasons for her to not use them. It was an issue of responsiblity (maturity) and our (Mom and daughters) perference. The major concerns as mentioned a couple of times is TSS - which is caused by leaving the tampons in too long. I was told that if she is not mature or responsible enough to know that she must change it out every 4 hours then she should use the pad until she was.
I was willing to let her try it if she wanted - she stated that she was. I showed her by diagrams and explanation what she needed to. I gave her privacy why she tried to do it herself...... She was too scared to even try it. That told me right there- she was not ready to do it.
You know your daughter and she knows herself. If you think that she is ready - let her try. She will tell you if she is or not.
I know the first time I tried to use a tampon, I was in the bathroom for at least an hour crying because I was terrified. I was not mature enough at the time. I tried to us OB the first time and OMG - there was no way I was doing that!!!!!
FYI - I did find that Tampax makes tampons now that are "slender" with applicator.
Good luck and trust your instincts!