Two questions? How long is it going to be not in use? And, a 300mm f2.8 is a pretty big lens, how much space do you have to store it in?
My cameras really only sit over night without being used. I almost never remove some lens from them.
I doubt it actually matters so do which ever you prefer. But if you are talking a long time you may want them in a case or some protective item.
EB
EOS 1DX and many lenses.
