Oh sorry didn't know such rule. My bad. About that question I don't know for sure. B I guess. would you be kind to tell me? Thank you
They are both possible, depending on your meaning. One of the options means that the hearer hasn't had the chance to be surprised yet.
Consider: A: "Would you be surprised if explained all this to you [now or later]?" B: "Would you have been surprised if I had explained all this to you [yesterday]?" You can see that these mean different things, and you'd choose the one you needed in the circumstances. The use of "had arrived" makes it more difficult, but they still both work.
(I'm sure ems was after more than a guess. You need to try to work it out.)