I second Robert. It's best to either go there and register/reserve, or if you're lucky you can do either of the two by phone. Good luck and God Bless!
Since it is no longer walk-in for that test, you would first need to go in and add your name to the list. If you are not able to go before 9am, it may be easier to call mid-afternoon and ask if/when they re-open the list later that day.
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