When I had my old work flat I used to have a cheaper rate during the day (10am-4pm) to encourage them so I could get my money earned by mid afternoon and get home early and it worked fine. I don't think I had more than one or two punter 'confused' by the timings or when the cut off was in at least four years of doing this and the best advice I can give is to be very clear in your ads and make sure all arrangements are confirmed in writing (so by text rather than over the phone, or email if you use it) to remove any chance of 'misunderstandings'.
This is now my practice with any new clients I confirm by email or text, receipt of deposit, balance to pay cash, time, date, duration, location, confirmation time.
Funnily enough one of the confusions was a guy who complained I needed payment at the start. Yes to avoid misunderstandings like this. The other told me he had not read the full sentence on my website, only the reduced rate not the hours it applied to. And despite my full rates being clearly displayed higher up the page.
Anyhow all clear nowadays.