I plan to attempt this exam in early to mid January depending on how well I feel I know the material. I want to knock out DCA about a month after that. My goal is to clear VCDX by the end of next year.
Here is my study plan so far. I am totally open to suggestions.
I have read the 5.1 Clustering Deep Dive book (It is excellent by the way - if you havent read it).
I have completed the VMWare VSphere: Design workshop.
I am now in the middle of Scott Lowe's "Designing VMware Infrastructure" course from TrainSignal.
After that I am going to read Scott's VMware vSphere design book. I believe this is not really geared to 5.x, but from a design standpoint I dont think that matters (that much).
Lastly, I am going to read through as much of the exam blueprint material as I can. About a week before the exam I plan on going through the Trainsignal course one last time just to cover anything I may feel weak on. I also heard great things about the vBrownbag videos, So I will probably give those a shot as well.
From what I have been reading from DCD experiences this seems to be sufficient, but like I said if anyone has suggestions or comments I am all ears! 
I passed my VCAP5-DCD last month and my preparation strategies were the same as yours except I read through the 5.0 Clusting Deep Dive book instead. Be sure to check out the tutorial on the visio like design question so you know what to expect during the test.
Good luck
