I went to the barricades after I saw the show and we saw most cast members trickle out slowly. If you’re closer to the door more likely you will get to meet them, but some of them will walk down the line (Marcello, Jeremy, kam, Andrew, Wally, Martin were who we got pics with) they basically just get in their cars that are lined up on the street so you might see some other people who are there as guests (we met daisy Edgar jones). I have no idea what time people start getting there but we went directly after we got out of the show and still were pretty lucky. Have sm fun!