Greetings. I will be arriving in DC by auto late on a weekday, and the next morning I will need to be at the White House for a tour at 0830. I will be taking the metro to the White House. Obviously it will be very busy with commuters (from Friendship Station to Metro Center). How do I buy tickets? Easier to buy them the night before when I arrive? The morning of? Is it a kiosk or a person? Long lines? Credit card okay?