
There's no age limit on age you have to handle, I first enterd a ring at 2! And also you can get your own affix (Aslong as you pay your money I don't think the KC cares about your age! ;)
However, be prepared to be knocked a little for your age. I have found over the years, although less so myself and my brother have had people who haven't quite "taken" to us, we can only assum due to our age.
HOWEVER the majority of the people are very encouragiing, afterall it's us young-uns who are "the next generation" and will continue to strive toward maintaining a breed for many years. :) (So why is it some people won't share their knowledge I don't know!)
Also, as your 17 have you heard about the young kennel club? It's a club for those age 6-25 who have an intrest in dogs and though here you will find many like-minded people of a similar age to yourself. :)
Also I assume you have found a breeder and on a waitiing list as you say you are getting a pup in near future? If a good one they will only be too happy to help you start your own line I'm sure and they will be an invaluble source of information :)