And always use the open jug first. It probably doesn't matter but I don't like the idea of a jug of oil sitting open through multiple changes. Using it all up could take years.
From here on out keep an eye out for clearance single qts at the store. I found a bunch of QSFS HM 5w30 at walmart the other day for $3ea. I grabbed 7 and left some for another to snag some on a deal. Other places to look is marketplace, I got 7 individual qts of PP 0w40 SRT oil for $25 earlier this year.