My clinician wanted me to shave before the appointments, this allowed the root of the hair to be targeted with the full force of the laser. I believe for electrolysis you do need to let the hair grow out a bit.
Also , after treatment, you won't be able to wet shave for a few days and the laser will not get transparent or fair hair, so be prepared for patchy facial hair. It takes a couple of weeks for all the hair roots to grow out.
Oh, and a bag of frozen peas applied to the face afterwards works wonders to cool the face after treatment.
Good luck