Having needed up until the last day to secure my Cape buffalo, I would say focus on the buffalo first and then PG if time remains. On the other side of the coin, I shot my elephant on day one and had the whole rest of the hunt to hunt plains game. Had not planned on so much free time I hadn’t budgeted a lot for plainsgame.
My recommendation is to hunt buffalo first, since that is what you’re there for, then have a big budget for plainsgame in the event you get your buffalo day one.
