When and how to begin reading instruction has been a subject of controversy for many years. Early studies (Morphett and Washburne, 1931; Dolch and Bloomster, 1937) suggested that a mental age of six or seven years was required before children were ready to begin to read. This resulted in reading instruction being delayed for many children and in many developmental activities such as distinguishing shapes and colors, sequencing pictures and even such physical activities as crawling and skipping being considered "reading readiness".
Cunningham, P. (1988). Names - A Natural For Early Reading and Writing. Reading Horizons, 28 (2). Retrieved from https://scholarworks.wmich.edu/reading_horizons/vol28/iss2/5