Mine has been working as a T for about 6 years. She's only 3 years older than me. I didn't exactly chosen her, I chose the practise whe worked at because they had experience with social anxiety.
I was worried about her being so young, not because of her experience but because it was so close to my age. But it worked.

Before my current T I had a T who wasn't that long ago graduated and she wasn't really useful to me.
I've also had much older T's and they didn't really knew what to do with me either. So age and experience don't say everything.

If I would ever need a new T, I want someone who's over 30, but too old won't work either, I think.