The "identity and power stage" is reached by the time a child turns five, according to data on healthyparentshealthychildren.com. This means that a child's identity begins to take form by the time they enter kindergarten.
When is the last time you read your child a bedtime story? I've been guilty in recent years of being lazy and putting a tablet on my kid's pillow instead of snagging a hardcover from the bookshelf, but there appears to be data out there that implies these types of habits can be stifling creativity in young children.