First Deal on a Fannie Mae REO

I am about to make my first offer on a Fannie Mae Home Path home. It's going to be a live-in-flip. It's listed for 70k. ARV is 110-115k. My MPP is 60k, but I really want to get it for ~50k. How can I get the best price? Should I start by offering 40k. How long does this process usually take and what can I expect?

For all practical purposes, I am a cash buyer. I should have cash in my account for proof of funds by Friday and the "no investor" period ends after Tuesday.