1. There hasn't been a set date on when the updated DAT is going to occur
2. I wouldn't change my study habits at all. Cladistics will be removed along with experimental embryology, however, if you feel that you shouldn't be responsible for landing a relevant questions is a bit of a gamble. To understand much of how phylums are different/related, you need to study up anyways. Also QR is to be changed slightly, visit posts by the ADA for the breakdown. Still the same spiel.
If you note, the changes to the DAT aren't much different to what has been out already. Acquire some practice tests do some Googling. DAT destroyer doesn't differ much from the previous editions. (Yes they recycle the questions, and yes I have 2011 2014 2015 and have gone through each of them once.) I too am taking it in the end of May to apply this cycle, however I'm a senior and pretty much done (6 credit load), with a basic 8-12hr session at the library, as your 19 creds seems to be hefty. Chad's is like the bible to ochem and gchem and Cliff's AP will get you through further detail than you may need to really know (although I've discovered material in the destroyer that I thought I never came across in Cliffs AP.) If you're aggressive enough, you can bang them both out in 3 weeks confidently (Chad's OC GC & Destroyer sections). If I was in your spot, I would probably wait another 2 weeks or so to take it- get practice tests dialed to promise at least an extra point or two on the real deal- otherwise, your finals might stress you out.
