You might want to direct that question to the NRA and let us know what they say.
As long as you can get 4 individuals together, you can offer the class.
I know I and other instructors have conducted classes during the weekdays (or over several evenings). As far as I know, the NRA allows for flexibility in times/places. The NRA places emphasis on teaching in teams and having students act as "coach/pupil". Having four students allows for changing teams for various drills.