Training puppies is a lot easier than waiting and trying to teach an unruly older dog what is expected. I started training all of mine right away. Kyra was taught to sit, stay, come, wait and down by the time she was a little over 7 wks then I started teaching her tricks all before she was 3 months old. Jack was 2 months when I got him and I started with the basics probably the first day he was home, we are going to participate in agility next summer because he is only 8 months now. When he was around 5 months I started teaching him the "over" command by using uprights but I have not made him jump anything, I also slowly taught him the weave poles and he knew them before he was 6 months (the poles aren't in a straight line but are spaced out so there is less twisting and turning involved). But I definately agree training should start when they are young.