Definitely try one of the GSDL clubs in the link Stuart has provided.
As for the age you start training the puppy, everyone will say different and it depends on the puppy but, in my opinion I'd just house train them and make sure they're happy, healthy and social puppies for the first few months, wait till its finished teething and start your proper schutzhund obedience at about 5-6 months.
Tracking you can do with little scent pads from an earlier age if they've got good food drive.
Most important of all is don't try to do any protection before the obedience is good.
As I said those are just my opinions and lots of people will say different. Its also very frustrating waiting until they're 5 months to start training them properly but its like my old dad says, 'its not a race'