When Ziggy, a Border Collie puppy from Clovelly, hit fourteen weeks, his owners called Luke Buchanan convinced something had gone wrong. The confident, biddable puppy from a month earlier had turned wary of the vacuum, the postman, and his own lead. Nothing had gone wrong. Ziggy had hit a completely normal developmental stage that catches most first-time owners off guard, because nobody had told them it was coming.
Luke Buchanan, Owner of The Toe Beans Co and Sydney's Puppy Trainer, sees this pattern constantly: owners panicking at a stage that's entirely normal, or missing a window that mattered because they didn't know it was time-limited. Knowing roughly what's coming each month changes how you respond to it.
8 to 12 weeks: the critical socialisation window opens
This is the stage most puppies come home, and it's the single most important window for exposure to new people, dogs, sounds, surfaces, and experiences. Everything introduced calmly and positively now builds a puppy's baseline confidence for life. The 5 Golden Rules should already be running in the household from the very first day, not introduced later once habits have formed. Exercise stays minimal, short lead walks only, roughly five minutes per month of age, twice a day.
3 to 4 months: teething takes over
Teething lands in this window, and it's usually behind a spike in mouthing that isn't a discipline problem so much as a physical one. Redirect onto something the puppy is allowed to chew rather than correcting the mouthing itself, and don't take it personally. It eases off once the adult teeth are through.
4 to 6 months: adolescence begins
Commands that were reliable at three months can suddenly look shaky. This is normal, not regression in the sense of undoing progress, it's a genuine developmental shift as independence increases. This is exactly the stage where consistency across every household member matters most, because a puppy testing boundaries during adolescence will find and exploit any gap between what different people allow.
6 months: the socialisation window closes
The critical socialisation window closes at 6 months. Whatever exposure has happened by then forms the baseline a dog carries into adulthood, which is why the months in front of it are worth spending deliberately rather than hoping it sorts itself out. The target is around 100 genuinely different experiences before that point: people of different ages and appearances, other dogs, surfaces, traffic, the vet, lifts, umbrellas, hats, wheelie bins.
It doesn't mean socialisation stops mattering at 6 months. A dog goes on learning about the world for the rest of their life, and plenty of the adult dogs I work with have made up ground they lost early. What changes is the effort. Before 6 months you are building a baseline. After it you are changing one, and that is slower and needs more care. If your puppy is already past 6 months you have not missed your chance, you have moved from filling a blank page to editing one.
6 to 12 months: full adolescence
Exercise tolerance increases, but the joint-growth ceiling still applies, particularly for larger breeds, so duration should keep building gradually rather than jumping straight to adult levels. The boundary testing that started earlier tends to run hardest through here, and the rules you hold now are the ones that hold later.
12 months and beyond: settling into adulthood
Most dogs are physically closer to adult by twelve months, though larger breeds can keep developing skeletally for several months more. Behaviourally, a dog that had a consistent foundation through the earlier stages usually settles noticeably here, the testing of adolescence gives way to a calmer, more predictable adult temperament.
Sensitive periods: the stage that doesn't run to a calendar
This one sits outside the month-by-month run, and that's the point of it. Puppies go through sensitive periods: stretches where they become more sensitive to novelty, and things that didn't bother them before suddenly do. The vacuum. The postman. A drain cover they've walked over every day of their life. Ziggy, from the top of this piece, was in one.
They don't arrive on a date and they don't run to a schedule. Two puppies from the same litter can hit one at different points, which is why the age tells you nothing and the behaviour tells you everything. You recognise it by what the puppy is doing: hesitating at something familiar, taking a wider arc around an object, backing off a person or a surface they were fine with before, wanting to be closer to you than usual. Some puppies go through it more than once.
It's developmental, not a training failure. The response matters more than the trigger. Stay neutral, don't over-comfort, don't force exposure. A calm, unbothered response from the owner teaches the puppy the trigger wasn't actually a threat. Push a puppy who is already at threshold and you deepen the association rather than clearing it.
What to actually do at each stage, not just expect
Knowing a stage is coming only helps if it changes what you do. In the foundation phase, the task is exposure and the Golden Rules, not obedience polish. Through the sensitive periods, the task is restraint, resist the urge to comfort or force. Through adolescence, the task is consistency, holding every rule exactly as written even as the puppy tests every one of them. None of these call for a different method. They call for applying the same method at the moment it actually matters.
The thread through every stage
None of these stages are managed by a different approach. The same foundation, calm and consistent leadership, household-wide agreement on the rules, and a realistic read of the dog's arousal level, carries through every month. What changes is what you're likely to see and when, not the underlying method.
Want a clearer map through your puppy's first year?
The Toe Beans Co runs a free SKOOL community where Sydney dog owners get training guides, Q&As, and direct support from Luke. It's free to join.
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Luke runs regular puppy schools right across Sydney, from the Lower North Shore through the Eastern Suburbs and out to Campbelltown. Check upcoming dates and book your spot.
Frequently asked questions
Q: My puppy suddenly seems scared of things that never bothered them before. Is this normal?
Almost certainly a sensitive period. Puppies go through stretches where novelty lands harder than it used to, and something they used to walk past happily now stops them dead. Stay neutral, don't force exposure or over-comfort, and it settles on its own.
Q: Why did my puppy's obedience get worse around five months?
Adolescence. It's a genuine developmental shift, not a sign training has failed. Consistency across the household matters more here than at any earlier stage.
Q: Is it too late to socialise my puppy if we're already past 6 months?
No. The socialisation window closes at 6 months, and by then a puppy should ideally have had around 100 different experiences: people, places, things and dogs. Past that point you are working with a baseline that is already set rather than building one from nothing, so it takes longer and has to run at the dog's pace. It still works. A good share of the adult dogs I see are dogs who came to it late.
