@Samuel740 we often have requests for late check-in. When I say late - I mean really late, like midnight or later. It is due to late flights.
As we are off-site hosts this is really inconvenient to us so I state at my house rules we can do it but we charge it 10€ per hour post our check-in time. It means if they want to check-in at 11 M it would be 40€ more, at midnight 50€ .... It works, they mostly cancel their booking. The thing is - guests either don't read or do read but don't care so they are not ready to pay for the host's inconvenience.
So, if you can accommodate early check-in I would suggest you charge for it. If you can't then just say you can't because you are at work or you have previous guests checking out the same day and you need time to clean.