People really do talk some crap on this site! Claiming to live and work in this window cleaners utopia where the customer is always wrong,does what they're told,pays what they're told,keeps it shut and considers themselves lucky that you deign to keep them on for your non-essential service.
So far detached from the real world where window cleaners are ubiquitous and anyone treating people with such contempt would be sacked long before you decide to 'drop 'em'.
Attitudes along the lines of you should be out by 8am anyway,do it or your dropped are as ignorant as they are laughable and take no account of reality.
In our 24/7 society ever more people work lates and night shifts and may still be fast asleep,or work locally and are only just thinking about getting up,showered and ready for work,or have young kids to feed,wash and dress for school. None of whom want some window cleaner - wfp or trad - outside their windows while they, or even more so their kids,are wandering around the house half dressed,getting in or out of the shower etc etc....And these are just a few examples of the many people around at 8am,and quite reasonably some won't want a window cleaner hanging around. As for terms and conditions,yeah right,cos that'll be read with interest.
Why can't you just ask on a customer-to-customer basis and ask people what is and isn't convenient for their particular circumstances.Surely there'll be enough customers whose windows you can do at that time that you can leave those who don't want them done until later?...
Or on the other hand just go around giving it the big 'un,claiming to earn over 100k / year and telling your customers "shut it...or you're dropped."