I already know the both can be an answer in the following, but I'd like to know the difference in detail.
A: Can I borrow your hammer for a moment?
B: No, I'm using it. You will have to wait until I (finish, have finished)
"Have finished" seems to mean an action should be finished by some point in the future, and "finish" seems to mean something similar, but I'm not sure of the latter.