As trainers and behavior consultants, we are often asked "at what age can you begin training a dog?" We love it most when we are asked by prospective puppy owners, because the answer is: as soon as you bring them home!
Puppies begin learning before their eyes and ears are open. Smells and sensations provide important information about the world, and begin to shape behavior: moving towards warmth is rewarded with comfort. Moving towards the smell of "mom" results in feeling safe. From that point forward, puppies are never not learning about the world.
This means that dogs are learning every waking moment from birth, whether we are teaching them or not. So, what do we want them to learn? Left to their own devices, they might learn the following:
Jumping on people gets me attention.
When I'm bored or lonely, barking entertains me.
Pulling on leash gets me where I want to go faster.
People only pay attention to me when I steal something off of a table.
While these things are normal dog behavior, they are generally considered inappropriate by most pet owners (and their guests). But, without feedback and proper training, they are likely to become habits by the time your puppy reaches adolescence. So, what could they be learning instead? With your guidance, perhaps the following:
Sitting politely gets me attention.
When I'm alone or bored, my person will provide me with an appropriate activity, so I can just relax.
Walking next to my person gets me where I want to go.
People pay attention to me whenever I'm calm and quiet.
With some upfront effort, you can not only prevent bad habits from forming, but you can teach your puppy to offer polite, appropriate behaviors instead. And they can begin learning these behaviors as soon as you bring them home! It's never too early to introduce your puppy to training and establish boundaries in a gentle, clear way. Begin by thinking about what behaviors you like, and start offering reinforcement (treats, attention, play, access to the outdoors) when your puppy offers them.
Also, consider the behaviors you don't like - such as jumping, chewing, or barking - and make sure you're not inadvertently reinforcing them with your attention or access to desired resources. Finally, think about what you'd like your dog to do instead, and make it easier for them to choose that behavior over the inappropriate one.
When did you start training your dog? What was the first thing you taught them?