I think it is best to measure once a week for length (in a flaccid stretched bone pressed measurement) as this will help you see gains in length before they become erect gains. It will give you a good map to your workout and how well it is working for you. Erect once per month as erect gains come slower than flaccid stretched, I say once per month so you do not become discouraged by obsessive measuring. With girth every 2 months because girth gains come at the slowest rate in Penis Enlargement. This schedule will give you your best watch on gains.