All this time I've been thinking / I thought...
Could you tell me please which reaction would be best in the following context? Thank you in advance.
A: Do you have any plans for Saturday evening? Maybe we can go out for a drink?
B: I can’t make it on Saturday I’m afraid. I work Friday-Monday.
A: Oh, all this time I’ve been thinking you work Monday-Friday. / Oh, all this time I thought you worked Friday-Monday.