Take a few minutes to stretch your muscles, then start out slowly, increasing to full speed after a minute or two. Slow down again for the last minute or two and repeat the stretches. There are five recommended stretches, each done for 20 seconds a side. They should be gentle and painless. With your feet flat on the ground and one foot ahead of the other, lean forward, bending just the front knee.
Exercise is most effective if done in the late afternoon or early evening.
If you absolutely can't do it then, exercising earlier in the day is better than not exercising at all, but you will probably need to exercise longer for the same effect. Don't exercise just before bed as this may interfere with sleep. Some patients find that exercise provides an immediate benefit, making them feel more alert and comfortable for several hours. If you experience this effect, you may want to try exercising on awakening and at noon as well. Some patients for whom this works may not need medication.