There is a wide range of "normal" when it comes to onset of production. Is your bird from hatchery/production type lines or from a breeders show quality lines? The focus of the breeding for a given line can have an impact on the overall production and rate of maturity. Also there is the factor that your girl "came of age" during the shorter daylight hour period of the year which can influence even first year layers. What are you feeding your girl? Are there other birds currently housed with her of production age and are they in production? Is she showing signs of physical readiness to lay?