It's around the ages of 3,4,5. Right in there, a child needs to learn the alphabet, and the most primitive sort of phonics. Letters represent sounds; and all the words that start with the letter B start with the same buh- sound.
Similarly, all the words that start with any given letter start with the sound represented by that letter.
So, maybe you think that's all very obvious. Not at all. For the last 75 years, the Education Establishment in this country has tried to hide the alphabet and the sounds. Children were trained to see the design or configurational aspects of letters, not the sounds that the letters represented.
This was a grand triumph of stupid over smart. The name of this gimmick was Whole Word. The most important thing that parents want to achieve is to keep this nonsense away from their children. If you don't take preventive steps, then the children will go off to pre-K, K, and first grade, and some schools will make them memorize sight-words. At that point you may lose them, or reading may lose them.
For a very simple guide to early reading and literacy, see this new article on hubpages: THEY NEED TO READ. For ages 1-4.
Here's the main conclusion I've been pushing: most children--if you just kept them busy with nursery rhymes, singing, printing letters, in short, all kinds of verbal and literary activities--would probably start reading without a whole lot of specific training. The more verbal kids are going to read just the way the more musical kids can pick up playing an instrument. They make it look easy.
Unexpectedly, it turns out that it's the less verbal kids that need the most systematic instruction. They need to learn the phonics rules so they will feel in control. When they feel in control, they can start to slowly improve their skills. But if you take the kid without a lot of verbal skills and you tell him to memorize 50, 100, then 200 sight-words, he is totally lost. It's a bare beginning for reading purposes, but he can't even master that, not with instant recall. Everywhere he looks, he sees alien unknown words. A few years later they will say he has ADHD, he's dyslexic, he has mental problems...
Yes, he has a huge mental problem. His school made him illiterate. The Education Establishment made him illiterate.