It might be an idea to ask them next time your cleaning/collecting/chatting and just say ' I'm just putting feelers out to see which customers mind me cleaning from 8am? it's just as the days are getting shorter, it gives me a bit more time to get my jobs done '
I doubt many people will say no, I have a lot of customers who go to work or do school runs etc, and it's not as if I'm in their way- your not delaying them by cleaning their windows. Any new customers, just tell them you start from 8am (even if you won't be doing their house at 8am) at least they'r prepared for it them 👍