I played for a week or two before my DK2 turned up 2 weeks ago. I'd recommend doing so, I think it helped what would otherwise have been a very steep headset-on-off-on-etc learning curve and also helped me know what I needed to setup for voice attack and what bindings would work where for me when I couldn't see anything, which I'd say is pretty essential personally.
Plus I think it increased the impact of finally experiencing it in VR. I was enjoying myself a lot without it, but then the DK2 turns up, you put it on and you're IN THE GAME. Its absurd.
In terms of other games I'd recommend trying other VR horror experiences before shelling out for Alien Isolation. The things I've tried, I actually just find unpleasant! Like fun for an experiment, but I don't think I'd do it for fun. Also ED makes exceptional sense in VR because you're always sat down in-game. I find translated FPS experiences far less satisfactory. Again, good and interesting, but so far nothing has matched ED or even come close. There is a lovely demo called Vox Machinae though which I recommend trying, because like ED it sits you in a chair and contrives a way to keep you there whilst making a full-control experience out of it.