Walking Training At What Age Is Leash Training/light Walking Acceptable?

At what age is leash training/light walking acceptable? - walking training

I have a puppy of 7 weeks and Aussie is very independent (which is almost completely shed trained, etc.) and put) a dish for days. I wonder what would be the ideal age to begin training to walk on a leash and when I go in my backyard (I think about it after taking off during his wanderings when) all their shots. Thank you!