Helen: What time is the show?
Alain: 6 p.m.
Eddie: Do you have the tickets?
Alain: I bought them last week 
Eddie: Cool
Eddie: How much do I owe you?
Alain: 50$ 
Helen: I an pay you today
Alain: It's ok. Whenever it's convenient for you. 
The show starts at 6 p.m. Helen will pay Alain back 50$ today.