Hi Guest, my youngest cocker boy will be 2 in August and is still very much a juvenile!! :D He started at about a year perhaps, had settled down by 18 months, but still loves nothing more than being defiant when the mood takes him and then coming to mum for a soppy cuddle whenever he gets the chance-in amongst causing trouble with the rest of our dogs and cats! A lot of it is just his personality though, each dog is different, so unfortunately it just depends on what kind of pup you'e got yourself! Just remember to be firm with them, that you're the boss and try and enjoy this time as they can show themselves as real characters and provide much entertainment! Good luck! :)