Developing without the devkit

Need an advice from UE4 developers. I finally got familliar with UE4 development and ready to start producing original content. I just ordered my DK2, so it will be quite a while before I get it. The question is - will it be difficult to integrate Oculus Rift into an already existing app? I will be coding with VR in mind, but I don't know what obstacles I may face if I start developing right now, without DK. I read the Oculus SDK docs, and seems like everything is pretty straightforward there.