They'll most likely have you written down but won't prepare much until you arrive because it's a Saturday, people will be in line, and I've never seen them take proper reservations. Your best bet is to not only call and let them know, but also call day of both in the morning and when you're on your way.
Call and let them know so they can make sure to have the appropriate amount of staff on.
If keep calling. Probably during business hours.
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