After looking at the past year, the only thing that concerns me is the Jan 4, 2012 dividend. If we assume selling on ExDiv-1, anything purchased after Dec 19 would result in a loss (using the closing price of the stock). Factor in the bid/ask spread and time decay for calls, and there's definitely a potential for loss, assuming one waits until after AGNC's dividend to enter the trades.
For the other 3 in the past year...
Jul 3, 2012
Apr 3, 2012
Oct 6, 2011
ExDiv-1 was the best day to sell, and ExDiv-2 was the second best day, and by a significant amount for Jul2012 and Oct2011. ExDiv-3 and beyond were not nearly as good.
That's what I see right now. You did say you'd jump back in only if there's a drop in BMY after you're out of AGNC. Something for me to think about. Hmmm. Wish the ExDiv dates weren't so close together.