To be clear: leave the pump on only if there is no chance that your skimmer and drains won't get clogged with debris and that your filter won't get filled before your return. Otherwise, do what you can today shut it down while you're gone and go at it again when you get back.

BTW, for 1 gal., 3 qts and 1 c, I'd be inclined to put in two gallons. This is not exact.