I go through the nut and bolts of cleaning using WFP at my house, let them clean a couple just to get the idea of how the pole feels etc.. From this you can see if they have a natural ability or are totally useless.
From there I show them 2 to 3 cleans then off they go while I talk them through the windows they are cleaning for the rest of the day
Day 2 again they clean all the windows while I critique and help them get a technique going.
From day 3 I start giving them half a house to do with no supervision, but check the work when done, over the next week I check less and less assuming all is good.
All this is done over a 12 week period, after that it's about 6 months to learn the rounds
Darran