Father of a 4 year old boy here. The way you encourage reading, it seems to me, is to read books to your child and read your own books. If there's a micro-culture of literacy in your home, it's easy. A good time to read to your child is right before bedtime. It also helps with bedtime by easing the child into going to bed as a positive routine (instead of child feeling "I have to stop doing [thing child enjoys] because it's bedtime.")