In some of the cases you might need to cherry-pick testers with specific answers on their screener. You can achieve this by creating a screener with at least one question which only has incorrect answers thus automatically failing all respondents. After the responses start coming in, you'll need to manually check the answers in the participant list and allow booking for those you find the best suited.
After you've allowed the booking the user will be notified and instructed to schedule a session from the available slots. Note, since the users might not be available on those dates, you'll probably need to allow more users than you strictly require.