After cleaning their windows I now tell my customers what day I intend to clean their windows weather permitting, which is 28 days later so they can mark it in their calendar if they wish. (Some still manage to get this wrong).
About 10% have asked me to text them the day before which I reluctantly do because it gives them the chance to ask me to miss them or for them to ask what time will I be arriving.
I sent a text to a customer (this customer is a heavy drinker and wont let me get there before 10am) on Friday telling her I will clean her windows on Monday, Sunday she replied asking what time I would be there, I said, you are my 5th customer so my best estimate is 10:15am, I got there 2 minutes early.
I put up with her because I clean the insides too and it is one of my highest paying jobs. But I did tell her this time I wont be texting her anymore before the next clean, I will be there September 21st.
I can see her being dropped in the future because she has called before the day before I am due saying it is going to rain so do not come Monday, and it was not a bad day in the end.