None of the news posts or the schedule lists the actual hours of the event.

 I believe it is based on the hours the Fantasy Flight Games Event Center is open:

Friday

04:00 PM to 12:00 AM

Saturday

10:00 AM to 12:00 AM

Sunday

11:00 AM to 06:00 PM

Go to the Fantasy Flight Games Event Center page and click on the calendar … it should show you a schedule for all events there.

Hope that helps!

I see they've added the hours to the PDF so that clarifies things immensely. 

Based on that document, it appears it does not start at 4pm but at 6 pm.

 Although most events run by other organizations usually include a 'doors open' so people know when they can start arriving and this doesn't so it is ambiguous: Is it normal event center hours? Is it 6 pm? Is it something else?

It's like the writer has a hard time putting themself in the shoes of someone unfamiliar with the event center and FFG events and just can't see that is pretty much the most basic piece of information that people will want to see. It is just so odd since every other event I have been to run by other organizations always include that information.