I'd wait as long as possible if you don't need it this moment. Based on the changes in the past, I'd expect far more improvements to iWork than is predicted for iLife.
That's what I would expect too, had it not been for the fact that iWork for iOS was released just a few months ago. Judging by the recent reports about Apple still operating much like a startup, I'm pretty sure that they didn't really put any new employees to work on iOS-iWork and instead probably temporarily more or less halted development on iWork for the desktop. That might lead to the desktop release slipping further into the future ?
It's just a hunch though. I hope I'm wrong about it.