At this time, there is no RTM date set for 2014. I would lean more towards 2012 and get the project started. Especially if you have a select agreement and can move up for free. I'd give some consideration to the hardware side, planning for memory expansion, especially given the in memory capabilities of both versions.

Depending on the timing of release, you could end up developing on 2012, but upgrading and going live on 2014. I'd assume that it will take some time to build backend processes.

It seems like versions come out more often, with fewer ground breaking features, and better upgrade paths (not as many show stoppers requiring a lot of rework).