gluconeogenesis begins 4-6 hours after last meal and becomes fully active as stores of glycogen are depleted (10-18hrs)
In the early stages approx 90% of gluconeogenesis occurs in liver but with prolonged fasting (or lack carb consump) the kidneys become major players for glucose production as well
This topic is covered in depth in my books Knowledge and Nonsense and The Carbohydrate Files
thanks
coach hale
www.maxcondition.com