Originally Posted by
FlyingMoose
If your inbound is on time then a 1hour+ transfer at IAD is more than sufficient as there is no security between domestic arrival and international departure. If you do not have status you can purchase seating, otherwise it comes 22hours in advance. You could call them and ask for seating together as SK does tend to give families an unfair preferential treatment.
OP is probably referring to the fact, that United is notoriously bad in accepting online checkin on international itineraries (especially ones including other carriers), thus he won't be checking in until a few hours before his first flight.