Parent/Child Two-Way Awareness is Key

When thinking of optimal Parent /Child relationship, two-way awareness is a key factor. Language development is a part of that relationship. Children learn best from parents or other trusted adults, and older siblings. The relationship is a positive attachment that is an essential conduit for two-way awareness of teaching/learning.
When a parent or caregiver has an established relationship with a baby or toddler, they become almost automatically tuned in to the child's need for clear pronunciation. Perhaps by trial and error method , the adult becomes aware that baby will hear the words better if said slowly and emphasis given to each vowel and consonant. Ashley Merryman calls that style of parental pronunciation to toddlers "parentesse". She has stated that parents worldwide have been recorded using "parentesse" and that it is the best way to model words for developing neural networks of early language development.
I would go further to say that infant facial identification also plays a part, since well-emphasized sounds also create more distinct facial expressions that are another important clue for baby's mimicking process. Typically functioning human beings are infinitely responsive to tone of voice, sounds made and facial expression when interpreting verbal communication, not only of the speaker but also of the potential hearer.
How many times have you realized you need to repeat a statement to someone because they have a blank or questioning expression on their face? Adults keep trying variations of pronunciation until they see some sign of recognition on the child's face. So do the infants and toddlers. When they try a "baby talk" sound, they are generally imitating to the best of their nascent ability the general noises they hear. If baby hears their sound repeated back to them by their significant adult, baby is encouraged that he or she is on the right path. When parent or caregiver then refines pronunciation, emphasizing each sound-part of the word, then baby will try to mimic that. The two-way interaction has begun. The language learning process is underway.
That significant interaction continues , layer upon layer, as baby progresses into toddler, toddler into Kindergartner, and on. The more aware interaction parent and child have the more the neural pathways develop, creating lifelong learning skills.
The verbal/aural skills need to expand into the visual literacy arena by age 3 years optimally for most children. Simply reading picture books with the same "parentesse" progression of pronunciation that has been established is a natural flow to toddler perception. Adding the picture in the book and implying that it goes with a specific sound, is the decoding key for initial reading skills.
Once the toddler comes to experience successfully mimicking sounds and picture correlation, they gradually understand that pictures are symbols for objects. Early books include known or "similar to known" objects and some unknown objects. Initially the known objects are understood. Then the unknown objects give information that somewhere they too probably exist. This decoding of flat image pictures as symbols for everyday objects, is the next essential building block in the lifelong learning skills in the progression from language to visual literacy.

Visual literacy and developing language skills give a child information, confidence and reading readiness. This parent/child progression is vitally significant to the well being of the toddler as he or she faces group learning environments. As we stated earlier, typically functioning human beings are very aware of one another's reactions.
Just as positive reactions stimulate the confidence to keep trying, negative feedback from a classmate or teacher can intimidate the learning process. The best teacher finds it hard to control the most subtle facial expression of frustration, or concern. And most toddler/Kindergarten newcomers can read that expression as "I didn't do that right" or worse "I don't belong here".
The way around potential negative feedback from future classmates is to give a toddler ages 3 and 4 years old, ample early visual literacy experiences with the most tuned-in persons on the planet: parents or regular caregivers. Recommended: 20 minutes per day, seven days a week of picture book together time. This regular personal sharing will give the little tyke plenty of familiarity and confidence to move forward more easily in the Kindergarten group.

Parents: Believe in Your Toddler/Preschooler

When experts tell you your child has a developmental lag, keep believing that you and he can do anything together. Maybe he doesn't fit in some larger grouping and has to go to a special class for now, but the future is still wide open as long as you keep on reading and enjoying learning together.
The nurturing experience he has with you, one-on-one that includes picture books can establish neural pathways that become very significant in the long run. Lifelong learning skills are the point, and believing in him, seeing his open possibilities.
I say "his" because I'm thinking of 2 specific boys and their parents. One boy's mom who had always loved reading picture books with her toddler, was told he was too young to go into regular kindergarten, and again by his kindergarten teacher that he wasn't ready for first grade. Mom believed in him as being very bright , with great potential. She found a private school that had small class sizes, and individualized subject levels. They tested him and found a co-ordination lag that they felt would possibly disappear with normal growth. "Boys often have co-ordination lags at his age that effect reading readiness," they said. She was able to keep him at that school through first grade, where the teacher remarked on his advanced grasp of theoretic math, specifically negative numbers. He was able to progress in every subject at his natural rate. They gave him encouragement with reading skills in class, all positive, and mom continued enjoying reading picture books with him daily.
By second grade, mom could no longer afford the private school. She was concerned, hoping her son had received enough individualized support to blend with a regular class. He did very well, got A's in every subject. Mom only had to ask his public school second grade teacher not to yell so much at the children. Mom explained he had a very kind supportive teacher the year before and found her yelling distracting. She tried a more gentle approach, which benefited all the students, and he led his classmates even in reading.
That boy just graduated from college summa cum laude, with a strong literature curriculum, and advanced writing, in a generation that is generally considered to be lacking in literacy skills. Also, as a young father himself, he has always read to his son, always believed in him , who is doing well now in second grade.