I have heard many moms say that any books that gets a child interested in reading is a good book. Although I understand the sentiment, I disagree with the concept. I think that what a child reads is as important as getting a child to read. Filling a child’s head with books that are devoid of imagination, use poor grammar, contain poor imaginary, are only surface and not mufti-faceted, do not educate or inspire but serve as empty calories in the world of food for thought. Reading can open a world of imagination, fantasy, inspiration, and experience. A book allows you to be places you can only visit in your mind, such as a fantasy world, the past, a key historical moment or even the future. Books can make history personal and real to a student who wonders why he must study Alexander the Great or ancient Egypt. Reading living books help develop a critical mind, enhances writing skills nad provokes ideas. This begs the question, “What are living books?” For a great definition click here.
When we serve empty calories for literature children do not feel inspired or seek knowlege. A parent or homeschooler needs to develop a healthy serving of living books for a very young age. Ambleside Online has books lists for preschoolers up to high schoolers. I highly recommend beginning there developing your own booklist. The sooner your start engaging your child in quality books the sooner the child will learn to enjoy wonderful arts of literature. This enjoyment will bring a curiosity about life and history to the child which will translate into a love of learning for a lifetime. Learning and eduation are a lifestyle not a means to an end. 
Here is what Charlotte Mason said about books:
We reject epitomes, compilations, and their like, and put into children’s hands books which, long or short, are living.(Vol. 3 Chapter 20 Suggestions Toward a Curriculum, p.226)
This habit should be begun early; so soon as the child can read at all, he should read for himself, and to himself, history, legends, fairy tales, and other suitable matter. He should be trained from the first to think that one reading of any lesson is enough to enable him to narrate what he has read, and will thus get the habit of slow, careful reading, intelligent even when it is silent, because he reads with an eye to the full meaning of every clause.(Vol. 1 Part VIII–Reading for Older Children, p.227)
The most common and the monstrous defect in the education of the day is that children fail to acquire the habit of reading.(Vol. 1 Part VIII–Reading for Older Children, p.227)
Therefore, the selection of their first lesson-books is a matter of grave importance, because it rests with these to give children the idea that knowledge is supremely attractive and that reading is delightful. Once the habit of reading his lesson-book with delight is set up in a child, his education is–not completed, but–ensured; he will go on for himself in spite of the obstructions which school too commonly throws in his way.(Vol. 1 Part VIII–Reading for Older Children, p.229)