It depends on what's wrong with your eyeglasses. If your eyesglasses just loose a screw, they can repair it for just one minute if you take it in walmart Vision Center. If your broken your eyeglasses lenses or frames, you may require to buy new lenses or frames to repair. They may need more time to make lenses or reframe your eyeglasses. So, just find it out yourself. Don't worry. It is not a big question.
My friend has repaired her old eyeglasses at Walmart before. I remembered that she got her final repaired eyeglasses after a week. However, according to the damage degree of the eyeglasses, the time of repairing may be a little different. You may call them and ask for the detailed information which may not delay your use.