You choose your time but buy the tickets ASAP because they sell out fast. Also check the Ghost Bus schedule if you plan to prepay for parking.
Check out the last time for tickets entry on the date you want. It's 10:30 today. But it may be different on some days and as it gets near Halloween . How long it takes depends on when you get inside. There is a long wait for ticketholders too but at least you are guaranteed to get in . Check out the FAQs https://secure.interactiveticketing.com/1.23/0152ad/?slot_date=2018-10-23#/select
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