"Are we supposed to ask for the hours exemption before skill test?"
I would say "Yes" as a candidate has to have completed everything necessary for Licence issue before being tested.
Until the exemption was issued a candidate would not have completed the required course of training. Who issued the 'Course Completion' Certificate?
The above, obviously, a paperwork exercise in this case but....
A candidate would not be too happy to have taken, and paid for, a test to then find an exemption would not be issued for some reason.
Hence the requirement on ATOs/RFs and Examiners to ensure any candidate has completed all required training prior to test.