It's not about what time he starts, but how long the crazy fucker feels like playing till!
Usually a school night gig he's on the decks by midnight, being a friday night, could be 1-2am before he starts and he'll probably play till closing time...and beyond!
I recommend an early dinner, then a 4-6 hour disco nap...up at 12, shower and shave, on way to club at 1am, then home again at 6am for some sleep before your exam...best of luck with it!