Depends. If your baby is normal then eyesight starts to develop when the eyes are open. There is a constant communication between the signal from the eyes and the brain which interprets the signal. This takes place over several years but there is continuous improvement in the normal. If there is a problem, you should see your pediatric ophthalmologist as soon as you can to protect the sight.
Immediately. Your baby can see right away. They can make out some facial features at close range from birth. Sight continues to improve and sharpen about every 2 weeks.