It's very easy now to check currencies before the trip starts. Often times I'll text the day of (assuming no one has swapped/dropped or banged out sick ) to see what their preferences are. I never got the "captain flies first leg" thing here. If my FO's need a lading for currency, one is flying out, one is flying back. No skin off my back. We do have many here, captains, that insist on flying the first leg over currency be danged. Never understood that mentality here.