I would suggest you arrive on Friday after 3.00pm, this will give you time to prove your bone fide and set up so that you can be bright eyed and only slightly hungover on Saturday when you meet your steward leader.
It will also give you time to orientate yourself or set up your own walking sat-nav.
You should find some common ground in between your duties but as Les pointed out it might not be in the 'official' programme.
Best of luck