I can’t help but chime in on this topic! In my weekly in-person class, which is mostly NW2/3/Elite dogs, we have one puppy who just turned 1 a week or two ago. He’s been in class since he was about 12 weeks old, but he most definitely is still on primary — exclusively. And over the past 9 months, we have watched him learn to solve problems: to know when the hide was over his head, to know when there was still something to find, to access what seemed at first to be inaccessible, etc. I’m not sure when our instructor will decide to put him on odor, but it has been so much fun to watch this little guy develop (and I say that with tongue in cheek, since he’s a male bull mastiff!!!). He is going to be one awesome nose work dog when he matures!