Superday Related Advice

I have a super day with one of my top choice firms very soon. There are 3 days for the super day (2 spots on the first and second day and 4 spots on the last day), and I am going 1st on the last day as I feel a little underprepared. Will going on the last day put me at a serious disadvantage? I am aware that going early is preferred, and there is still a spot left for the 2nd day. Is it worth going early despite not having the best preparation? Do firms have a set number of candidates that they talk from a superday despite the quality of candidates? Need some advice as I am pretty confused right now.