If it's something as simple as an attack coming in on a certain port, it would be wise to block that port, as long as doing so doesn't impact doing business as usual.
A while ago there was a 0-day that had to do with how Windows handled certain pictures. MS wasn't going to have a patch out for 3 weeks, but in the meantime they had a work around which was de-registering a certain DLL. A quick script later, and I had all of our machines fixed up. When the patch was out, everything was ok.
Part of the problem is, there's lots of 0days out there, and attempts at blocking all of them would probably be an exercise in futility. Follow good security practices, teach your users about suspicious activity, and watch your traffic.
The last 0day we got hit by, one person executed it upon himself when he got it via an email. During the next training session, he became the example of what not to do, we haven't had an issue since.