The first months in a new puppy's life are an amazing time for learning about new things. In these first few months, nerve pathways develop and are only retained if they remain actively used.
Incredible though it may seem, this means that the range of situations your new puppy encounters actually influences the nerve pathways in their brain.
So making the most of this period to socialise and teach your puppy as much as possible is key to a healthy adult dog. Understanding their behaviour and needs during this time and training should be done in tandem with socialisation.