Every three weeks. After I cut them I usually file them a little so that they are smoother. I don't worry when I do Bella because her nails are light colored and I can see the quick. When I first got Ripley his nails were VERY long and they are black. I have been taking just the tips off because I am afraid that the quick has grown way down. I did make him bleed once and I felt just awful. He has learned to trust me again though but I still don't think he feels very comfortable with the whole idea.