It is beneficial for kids to be engaged in reading, being read to and verbal interaction with both adults and children. So they receive the most benefit staying at home with a parent that is focused and dedicated to stimulating their child through play, reading, conversations, and walking/exploring out doors. If for what ever reason, a parent can't spend at least half of their day stimulating their child's mind with new experiences everyday, then preschool is very beneficial, the sooner the better. If a parent is not a fan of knowledge, did not finish their studies, and does not like to learn knew things everyday, then the child will benefit more by going to preschool. But remember, no amount of preschool is beneficial if the school/teacher(s) do not know how to engage the child in a way that makes the child want to participate. If at all possible, avoid any preschool that has nap time, brains are like sponges until you teach a child to turn it off by forcing them to sleep or lay quietly for 20 minutes or more in the middle of the day. When I child gets tired during the day, let them sleep, if they are not tired let the learn, study or play.