If you find a corneal ulcer after wearing contact lenses, You'd better visit eye doctor immediately and get it controlled immediately, or it is likely to cause more severe problems like blindness. So, you'd better make sure your eyes are healing before you wearing contact lenses again. So, the longer you wait, the better. I heard that you'd better wait at least two weeks after your eyes healing so as to make sure your eyes won't get hurt again when wearing contact lenses.
The healing time of different people varies. Generally speaking, the longer you wait after a corneal ulce for wearing contact lenses, the better it will be. It is advisable to wait for at least 2 weeks after the corneal ulcer get healed, then you can wear contact lenses. However, some people may wait a lot longer. The best way is to consult your eye doctor and follow his or her instructions. Otherwise the contact lenses will cause damage to your eyes.