It will be a 2:30pm start, and the casino doors usually open at noon-ish (this is what"s happened at all the previous events, it might be different this time).
To get on the reserve list in the past, some people have been there from 9 or 10am. However, for the last event (the European one), people were literally walking in and getting a seat at 2pm.
With the change in the law, alternates are also allowed now. This might mean more people turning up on the day hoping to get a seat. Difficult to know really until after the event.
If it was me, I"d plan to get there early, for say 9am. Bring some food with me and see what"s happening. It might be overkill, but if I"d travelled any distance to get there (and booked a hotel, etc.), I"d want to make sure I got to the front of the reserve list.
I"m sure Des will post with the confirmed times for opening etc.