It's hard to tell how many people will be signing up in the morning. This is the first year that this tournament is being offered as a one-day C tier. For the last 5 years, though, Guy has run a B tier 2 day tournament in early fall at Seatac that has generally filled. Apples and oranges, though.
But as I will be capping this at 72 players, if you want to guarantee a spot, I suggest you get there early. If it fills, I will turn late arrivals away.