I've never seen that as a requirement.
Well, you should wash your hair down there. Which, as a matter of fact will be done automatically if you washed the privates.
Most of my appointments are before noon, in fact on or around 10 am and I always shower in the morning at home and when I get there, I wash my face, my sac and my crack. In very few cases, if the appointment is after 12 pm, I wash it all except hair. My hair down there is all clean shaved but I have light hair in my crack and I can't do anything but to clean the 'hole' area thoroughly.