I really am hesitant to answer this I don't want anyone to think that I am making assumptions about younger swingers but think that it is important to make some comments. Can't believe I missed the original question.
I have met 2 very young couples one where he was 20 and she was 21 and another couple where she was 22 and he was 28.
The first couple had come over from the States into Canada and it was obvious that they were taking advantage of the difference in drinking age from Michigan to Ontario. It was their first experience at a swingers club, they were very disappointed in our mostly 30's crowd and he was very drunk. We did spend some time talking to them and I don't know how long they had been together but they did not live together. They were not ready for swinging, I think they had a fight in the club but we left before they did so I really don't know - they didn't come back as far as I know.
The other couple had both been married to other people before and had been swinging for some time before we met them. While we found a definitely lack of things in common I think that each of them knew what they wanted in a swinging relationship and had worked things out by the time we met them.
My own first swingers experience was a threesome MFM at around 18 or 19. Of course the web was not around so would we have even know what we were doing was swinging??? and I did meet a bi-female (newspaper ad) at around that time but never went anywhere with it. I am sure that we were not mature enough to deal with it anyway.
BUT I don't doubt that some people are ready for it.
I think that younger couples are routinely disappointed to discover the age of the majority of the swingers attending clubs and feel uncomfortable because of it not just age but the music is geared to a slightly older crowd as well...
I do think that some time alone together to establish themselves as a couple is important. And I think that the way you approach swinging it is important too.
I went back and read the original thread and don't really know how to integrate the idea of very young singles into the lifestyle ... but then singles have enough difficulties integrating into the lifestyle but to add age into the equation is yet another obstacle.
Naughty A.