My shih tzu ate 2 chicken wings whole and I called the vet he said to feed him bread and to watch him and if he starts vomitting or bleeding from his bowels to bring him in immediately. How long until I can feel he is okay?

You will have to wait and watch for them to pass. It could be a few days. The bread works great for cushioning the sharp edges of the bone. You can soak cotton balls in chicken or beef flavoring, and try to get him to eat that too. The bread should do the trick though.

IF the bones weren't cooked then he should be OK.
Just keep an eye on him like Aurora said, signs to watch out for are excessive drooling, lethargy, whining, trouble or inability to pass stools.

The dangerous part with giving a whole wing is them swallowing it, they often get stuck in their throat, but once they make it down to the stomach it starts to digest and break up.

Next time grab a meat mallet or even just a hammer and hit the wing a few times to break up the bones.