You will probably get a variety of opinions on this one. It depends on whether you use open oar locks or pins & clips, how wide your boat is, and personal preference. I use open oar locks and have tried all 3 methods (pull oars in, blades forward, blades backward). For me, I can ship faster & easier with the blades forward. My rafting buddy always ships his oars back, and gives me crap for shipping mine forward. His says I'm asking for an oar handle injury. I can usually ship forward and still have control of the oar handles. When I tried shipping back, I had to lean way forward or even come up off my seat to get the oars back far enough. I don't want to leave my seat in a rapid, and this method wasn't as quick for me as going forward with the oars. Pulling the oars in doesn't work well at all for me. It's too cumbersome, slow,and potentially dangerous. Pulling in 9.5 feet of oar in a split second doesn't work very well.
I'd say try either method and see what works for you. But mostly, keep control of your oar handles so that hitting a rock with the oar doesn't cause an injury.