I'm a teacher currently on maternity leave (Reception/Year one) Reading (& writing) is a developmental stage and usually it all "clicks" into place when they are ready. Usually with the younger ones it is in year one and occasionally year 2!!
Most schools now follow a Phonics Scheme of some sort or another and introduce more formal reading later.
We have adapted Jolly Phonics and other schemes to suit the needs of our children, and most children won't have a reading book to take home till they have completed/are near the end of our scheme. (they tkae home a sound books consisting of 6 letter sounds & a list of around 8 words that can be made with the set of letters they are on)
However, we still share books with all the children 1-2-1 and in small groups(4) where we talk about turning the pages in turn, 1-2-1 word correspondance, reading left to right and down the page etc (pre-reading skills)and most importantly (no matter what age) comprehension skills.
Although the majority of children learn to read & write using phonics, there are always a handful that learn through sight memory and/or in a context. These are the children that would benefit from having reading books early on.
I would argue against Forehead's comments, I have seen many children pushed & pushed with their reading when developmentally they weren't quite ready & suffer huge self esteem problems that plague them throughout their school days! That maybe what she has experienced!
The best approach for now is to continue doing whatever school has asked you to and read to/with DS, point to each word as you read, discuss pictures and the story (comprenhension skills outweigh technical skills in any assessments inc SATS) Develop an interest in books with him and allow DS to see you & DP reading for fun(especially DP)(not just bills & newspaper)and take it at DS pace!