You really should do a 'Welpenförderung' class, a class specifically designed to promote age-appropriate puppy development, run by a trainer who is qualified to do so.
Be aware that not every 'Welpen Spielgruppe' is the above. There are still a few people who run puppy play groups as a free-for-all, which can do more damage than good.
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I don't know anyone in LU, but you might start by looking into the Kynologischer Verein Luzern. I see from their website that they run a Welpenförderung class, as well as adolescent classes:
https://www.kv-luzern.ch/kurse/welpenforderstunden
A colleague in Kt LU (but I think closer to the AG end) goes to Hundeschule Fee:
http://www.hundeschule-fee.ch/home/frameset.html
If you are able to travel to Zürich, the ZH Veterinäramt keeps a list of trainers who are qualified to do the Welpenförderung class within the cantonal List 1 set of obligatory classes, here:
https://veta.zh.ch/internet/gesundhe...Ort_190129.pdf
IIRC a couple of ZG dog owners have recommended training schools - I'll have a browse around and link those when I find them.
Can your breeder recommend someone?
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The good news is that most of the trainers you will meet in Switzerland espouse positive reinforcement, force-free training. The various umbrella training/sport/general canine organizations here support and promote this philosophy.
But there are still a few old school trainers around whose methods I would not allow around my dogs, so due diligence is needed. Always ask to sit in on a session without your own dog present so that you can see how the trainer interacts with the dogs and owners. Choose someone with whom you feel comfortable.
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Something to consider down the line, after your puppy is a bit more mature, is the new National Hundehalter Brevet. This is a voluntary set of courses, designed as a replacement for the now abolished SKN:
https://www.nhb-bpc.dog
In fact, if you are a first time dog owner in Switzerland, the NHB Theory course would be very valuable to you, an opportunity to learn more about the rather unique expectations and responsibilities dog owners face here.
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And I'll just hop up on my soap box for a moment:
I am a huge fan of life long learning. I look at involvement in a Hundeschule as an ongoing activity, not something to check off a to-do list. My dogs go to our Hundeschule weekly (or more) their entire lives long, from the day I adopt them through their senior years. Dog training classes run the gamut from serious to fun, there is something for everyone. Dogs need mental stimulation as much, if not more, than physical, at all stages of their lives.
As do we dog owners. Getting involved in a Hundeschule was the best thing I ever did for me .
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All the best to you and your furry friend.