Last two jobs, the pee test is prior to the offer. But the interview was also in virginia, and they said they send it to labcorp... I dunno, I was surprised too.
It was a fun interview to do. Had several different interviews with different groups of people. They gave me some business cases prior to coming in and went through them with the manager. Then they had me prove I am an excel expert and some gmat/lsat type questions. All on 4 hours of sleep, since I got to the hotel at 1:00am.