2-3 years seems to be SpaceX's preferred timeline (and they've hit most of them so far)
The craziest part is that I think they can actually do it.
http://www.spacesafetymagazine.com/2013/01/22/nasa-passed-fa...
The Grasshopper experiments are also going along really well. I am shocked how quickly SpaceX is achieving milestones.
But they've certainly hit all their milestones, eventually, which is much more than can be said for nearly every other private space venture.