They want you there and your party members (guests)there a little bit early so they can get everyone checked in and their numbers for the block of time you paid for so that you aren't using up some of your paid time standing around waiting
They would like you to be there 30 minutes early but a lot of people do not. So you do not have to be there 30 minutes early if u do not want to be there 30 minutes early.
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