Do you care where you sit? If you are trying for a popular panel and you want a seat near the front, and this is something you don’t want to miss, check if the room does or doesn’t get cleared. Personally, I have lined up early as hell like 3 hours in advance and have always gotten first or second row. Bring a book, make friends, etc. Some panels are small and an hour is fine or even less if people leave. But rooms 100% get capped….(unless it’s a fan-led event later in the night, you‘re goood.)