You do not have to be there on thursday though if you are you can take part in the early bird party, free food and free product giveaways raffled off with free entry
Friday is a test and tune day and one qualifier so you do not have to be there either.
Saturday is a two qualifier day and true street day so if you plan to race Sunday you have to be there Saturday.
Sunday is race day.
So if you cannot get off work Thur and Friday, you can still participate in the event.
the only day you cannot show up and race is Sunday so worst case, if we are looking at this way, is you need two days for this.