Answer
It is recommended that lecturers arrive at the lecture hall before the students, so that the examination sheets are placed face down on the places of the students. The admission to the lecture hall will be possible at least 45 minutes before the exam.
Alternatively, the examination sheets can for example be placed face down on an unoccupied row of seats, so that the students can pick them up from there.
The occupancy-plans for presence-exams can be found on the Room Information page.
You can find more information on presence-exams in the Guideline for Presence Exams at TU Wien.