I don't like to see a novice dog without any "come forward" on their stock. Some stockdogs are born without push and then there are some trainers who take the push out of the dog before the dog has had time to mature.
I'm thinking it's best to let the dog do ranch type work while allowing the stock to teach the dog, at least to some extent. Training for ISDS type of course work is mentally stressful. I think it takes a lot out of a dog. Quite frankly, I don't enjoy "course work" anywhere near as much as a "ranch type" trial work and neither do my dogs.
The other day I was a trial and I heard exhibitors remark on how calmly and nicely the many novice dogs worked their sheep. I, for one, don't like to see that. I like to see a novice dog with a lot of zip to it. One that makes mistakes, but shows some signs of thoughtfulness and stock savvy.
It's difficult to find that perfect balance. When looking for an ISDS trial dog, certainly an older dog is a more certain bet. That way you can see their working style, before making a decision. It will cost you, but if trialing is your bag, I'd recommend it. Pups remain a bit of a crap shoot.
I'm still hoping one of these days to breed Kilt again. I'd love to get her attitude and stock savvy with just a bit of thoughtfulness added to it. And, I'd like another male. But, for now, Jet is the only male dog around here. The rest are all bitches. :0)