Even heard of the EVGA step-up program? It is perfect for current situation. Buy a cheap EVGA 1080 Ti now and wait for the real launch and benchmark. You've got 90 days to make decision.
I just bought EVGA 1080Ti SC2 when B&H got it for $599. Amazon even got a Zotac 1080 Ti for only $529 earlier last week..The price is dropping fast...