What is probably the time for the appointment?

W: John, it’s 7: 30. I wonder how much later they are going to be?
M: Oh, you know Terry and Susan. They never arrive on time.
W: Yes, but half an hour late! My dinner will be mined.
M: Oh, maybe they got stuck in traffic. You know what the traffic is like at this time of day.
W: Yes, but they said they were taking the subway so they wouldn’t get caught in traffic.
M: Well, they shouldn’t be late then. Why don’t you give them a call and see if they’ve left. Maybe they forgot about the invitation.
W: They couldn’t have forgotten about it. I was just talking to Susan last night. Anyway, let me just check if they are in. Their number is 2143556.