Varicose Veins

Those blue bulging veins which protrude from the skin, usually on the legs and thighs are called varicose veins. Spider veins look like short, fine lines, "starburst" clusters, or a web-like maze. Spider veins usually appear on the face, thighs, ankles, and feet. While all of the causes of varicose and spider veins are not understood.
The basic problem is that veins usually in the lower part of the body become engorged when blood does not circulate properly. The absence or weakness of valves in the veins, which prevent the backward flow of blood away from the heart, may cause poor circulation. In other cases, weaknesses in the vein walls may cause the pooling of the blood.
Varicose veins are more common in women, though men can also develop them. You may feel better if you avoid standing/sitting for long periods of time. Try to stay off your feet as much as possible and sit with your legs raised. Taking regular walks, and resting with your feet elevated, may improve circulation and reduce symptoms.
Wearing support hose is a good way to provide support for the veins. If you have them, put them in the morning upon rising before blood and fluid have pooled in your feet and ankles.Varicose and spider veins are usually just annoying, and don't have to be treated unless you are bothered by your appearance, or the symptoms associated with them. 

I would not wait till I have varicose veins before I start wearing support pantyhose. I rather start wearing support pantyhose now (coupled with regular exercise) to prevent varicose veins.