When I decided to switch I was only about 1 1/2 months from Tiger's release, so I waited and was glad I did. There's a growing amount of software out that requires 10.4.x or better now, but it's also been nearly 2 years since its release. I also had a chance to scour this forum and other sites to fantasize and learn all I could about OS X.
I didn't find Tiger to be too buggy with 10.4.0, but even now with 10.4.8 on my G4 Mini there are bugs that Apple still haven't addressed, although they are fewer with each update. And when I say buggy, I don't mean a computer crashing all the time like with Windows bugs; I mean certain things in certain apps not acting the way you want or the way they should. Sending a bug report to Apple almost certainly corrects the problem within about 2-3 updates, I find (once enough other users report the same bug).
So my points: Wait if think you need to, but since Leopard could still be months away, get your "paws" wet with Tiger (bad pun, I know) like others have suggested. And realize that no version of OS X will ever be free of bugs, even after several updates!