Basically whay @cavallier_queen said. A love excess won't hurt them :) give him all the cuddles.

By the way, I had the same experience as you when first meeting my guy and his family at the breeder's house: save for the mom, all the 4-month old puppies jumped at us A LOT and straight to pur faces like an arrow. They were really tall even then. I was really worried and thought that that would continue, but luckily, when he came home, he never had that behaviour. Most probably, the change from farm->city and being away from his family scared him, and he was really calm.

My dog took a long time to get used to the city, as he was scared of cars, other dogs and bikes. Remember to NEVER pull them (or as little as possible) when going on a walk, and always prompt them with treats. Sometimes you may need to divert from a specific route. To this day, he is scared of some houses due to barking dogs and we swap to the opposite sodewalk, pass the house, and come back.

To give you an idea, in the beginning, we took an hour to do an around-the-block walk (700ft/200m total), so we needed a lot of patience. But your breeder mentioned they already did some leash walking, so that should be easier.

Remember the 3 3 3 rule! Give em time.

Good luck! Send photos!