Before you take this project for your child, you should make sure that your child has learned all the alphabets of the language. If your toddler has started to go to the preschool, then probably he will learn to identify the alphabets.
However, learning to identify the alphabets does not mean that he can start reading the books from now onwards. At least this can be said, that your child has made up to the first step of reading books. You have to spend several months behind your child, before he can read his first book.
The next step of this project would be to make your child familiar to the simple rhyming words. These words should be read out to him again and again along with the associated pictures, so that he can now identify the word against its picture. You have to also initiate him into the learning habit for these easy and simple words.
After few days of regular study, your child would be able to memorize these words and can identify them either by seeing the pictures or by the word itself. However, you should never pressurize or force your child to follow a regular routine of study for everyday. You can also make him learn while playing or doing other works, when he is in a good mood.
When you are done with the rhyming words, you may take the easiest book with simplest sentences on the earth, to read out for him. Again this process has to be followed repeatedly, to register into his brain. You should read out each and every sentence at least 5-6 times whenever you sit with the book. While reading the book, you should point to the words.
This will create an exact replica of the words in his brain and thus he will start identifying the words. Following this procedure, eventually you should ask your child to read at least one sentence at a time.
Initially do not give him multiple books for reading as he might get confused. Start with one book and move to the next one, only after finishing the first book. However, later when your toddler learns to read books, you should arrange for a number of books, if you want to make him a real book worm.