Kipling looks a very sweet boy - lovely photo
It is true that the best time to introduce a puppy to new sounds, sights, scents in different environments and with different people is before around 16 weeks of age. The reason for this is that the earlier they are exposed to a range of new experiences the more likely they are to be more confident, resilient and cope well with meeting people, other animals, different places etc. However, there are a number of factors that will also affect how well a young dog adapts to life as he matures. The temperament, resilience and good nature of the parent dogs and the conditions in which the puppy was raised from birth being two very important considerations.
Did you get your puppy from the breeder or from another family and do you know anything of his life before you got him? We have had puppies we bred stay with us until 4 months or more of age if the family cannot take them earlier and they are ‘socialised’ by us before they leave for their new homes. We take them out and about and introduce them to different experiences so, if Kipling has had some socialisation before he came to you, you should not need to worry too much.
Other factors that are significant are whether Kipling was raised in a home rather than an outside /separate facility as even just being in a busy home environment will expose a puppy to household noises and probably a range of people too. Also were his parents of a good temperament and was his mother loved and cared for? Dogs raised in a barn or with the parents badly treated will be affected by the stress of their mother while those who are supported and loved and cared for in every way through the whelping and raising of their pups will be more likely to have relaxed affectionate puppies.
Even with the best bred dogs, raised well in every way, there can be differences in temperament and individual dogs can have things which spook them or which make them anxious but, if Kipling is coping well with his move to your family and fine with visitors, I would not worry about the 16 week mark. There will always be people who tell you what is ‘right’ and ‘wrong’ about how a dog is raised but Kipling is your schnauzer and you are the best person now to judge how he is settling in and coping with his new life in your family. Introduce him gradually to any experience you think may be new to him - traffic, cafes, shops or whatever places or people that are important in your life and where you need him to be relaxed. The love and care you give to Kipling is what is important and you will know if there is anything where he may need extra support to feel confident but it sounds as though he is doing just fine
I am hearing left right and center that they are best socialised before the
) I know that if he can't do one of 3 things when asked then he's feeling a bit anxious and we walk away. Give me eye contact, paws up on me or an object and nose touch. 
) -- and he was calm. I like your tips --- all of them.... they give me coping actions! MANY MANY thanks.... I am thrilled to be here (thirteen years after receiving my soul buddy Schubert)