Start now! It is important to help your puppy associate nail trims with “good things” so one that they look forward to this time. This is accomplished by playing with the puppy’s feet one at a time while rewarding with food treats. Do not clip any nails at this time. The slower you progress without forcing the puppy, the quicker he will pick up the fact that “when my owner holds my foot, I get lots of treats!” You then gradually increase the length of time spent holding the foot, start touching each individual toe, then clicking the clippers (a noise that can be scary to some pups), then clipping a toenail! Do not expect to be able to clip all his nails at the same time or to reach this comfort level within a couple days. Give him plenty of time and treats!