Both. Of course. You'll have time. Buy the 4K monitor as big as you can barely afford and get VR this fall/winter.But for me its VR sometime this year/early next for Elite Dangerous etc, or a new 4K monitor. Gah! Decisions! hahaha
Didn't I see Oculus Rift out in 2016?
And Elite Dangerous looks best on three monitors...very cockpit-ey. That said, it still looks amazing at 40 inches and 4K.
I run the Philips BDM4065UC - very happy with it.