Rachna,

Your question addresses a pertinent issue.  There really isn’t a magical age where children suddenly become engaged and fully understand textual content, but comprehension rather depends on the individual child and his or her prior experiences with reading.  A good age to start reading to your child would be as early as you can and often.  Reading aloud to your child and having them see you read is a great way to expose them to reading at an early age.  Whether or not you know that they comprehend the text, they are becoming exposed to the reading practice.  Young toddlers whose parents read aloud to them may understand the oral language while not always comprehending the text on the page.  However, through time, they may come to associate the words and the images in the book with what their parents express orally.

The age that children start to become engaged and understand text really depends on having the building blocks for reading.  Helping your child acquire these pre-reading skills is essential for helping them piece together knowledge to read for understanding
An example of a pre-reading skill is correlating an image with a meaning and a sound.  Young children and toddlers start to attribute these meaningful images as symbolic representations.  For instance, a toddler may attribute the physical logo of a store with the oral expression of the store’s name and the physical store itself.  The following article about reading for meaning concerns how identifying phonemes is essential for preparing kids for reading:

http://www.education.com/reference/article/reading-comprehension-for-meaning/

The following article also addresses the role of decoding in comprehension development:

http://www.education.com/reference/article/current-issues-reading-comprehension/

I hope you find these articles useful.  

Best,

Hayley

Here is another article that shows the developmental progression of children's reading capabilities.  It shows reading behaviors one would expect at each age from birth through adolescence.

I would say it depends on the child. Ages 5-8 is a good age bracket in my opinion.

I started reading to my daughter at about 11 months. At 13 months, a neighbour aged 8, taught her all the letter sounds in one afternoon. By 2 years, she was reading confidently and never had to sound out a word. She turned out to have a very high IQ and has developed into a great adult who is fulfilling her potential.

My daughter has a baby daughter herself now. She started reading (and singing) to her from birth. I am amazed how intently the baby listens. Her favourite books are those that rhyme. Baby is now 8 weeks old.

Whether Baby is gifted or not, I am sure she will grow up loving books and all the better for her mother's loving attention.