Retainer order?

Hi, I just picked up the first set of my Clear Correct retainers yesterday and they hurt my teeth really bad. Tylenol is not even helping. I took them out to look at them and there is a 6 digit case number on the retainer followed by a space and the number 3. Does that mean retainer #3. Shouldn't I have started on retainer #1? Just wondering if maybe the dentist started me on the wrong retainer?

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