11 days, I think?
From the instructions so far, they seem to have deliberately given themselves leeway to make decisions on that as the situation demands, with references to the fact that access may be revoked and offered to someone next in line, in time order on the list.
They aren't going to know how many people will attend/drop out until the tribunal is in session. They also won't know how well-behaved/problematic the observers will be, so I expect they will make the best decisions about how to use their time when they have a clearer idea.
If observers haven't read the instructions and make live commentary online (in the way that I don't think was prohibited in February), then they could still pull us all offline anyway. If people don't sign in for each session, they could offer places to next in line, but that could take up a lot of time, if very many people have made other plans or if the next person (x100) accepts a place but also drop outs after one day.
I am planning to sign in on a laptop in a room for my own use only, and will inevitably have to lock the screen and pop out to run errands from time to time. If that gets me evicted, eg if I fail to notice when I next need to log in, then I will just have to suck it up and hope someone else enjoys my place!