I would guess that those dates are US Pacific Daylight time. If the test center you are using is closed on the weekend, the last available day for you to test on would be the 31st.
I suggest you either find a test center that is open on the weekend, or take your test on the 31st.
If you feel you are not ready, then take the replacement test #342-356.
If you found this helpful please rate it
--Colin McNamara