I agree that meeting for the first time (when the first meet is also the first clean) is a good idea - not least so you can gauge if you are even going to be paid. Personally I'd try and aim for the start or the end of my day so I'd say "8.00/8.30" or "sometime after 2.30 but before 4.00."
But as mentioned it's good to mention stuff at the start at the outset on the phone ... so as your discussing you might say ...
"let me just set out a few of my business terms to ensure we're on the same page - I only take on regular 8 weekly customers and I don't phone or text beforehand as I've got too many customers to schedule (if it's a concern I say "you call me at about 7, 7 and a half weeks and I can look at my diary and let you know more specifically as I'm much closer to the time") - the first clean is always rather more than the regular price depending how clean they are. "
At this point I will know whether things are feeling right. If they are I go on to say ...
"As far as payment goes I prefer on line within 48 hours but can take cash or some of the elderly pay by cheque but that adds a pound to the price due to bank charges - even if you happen to be home I don't expect cash, you can still pay on line."
(That sets them up for not being there and me just turning up)
If they bring up a gate issue (and it's a normal solid 6ft side gate) I say "Well most other customers are happy for me to use my special gate ladder (a 2 metre top section with ladder mitts
) or give me a code or a key - if that's not acceptable and you're not in I just do the fronts and any accessible sides and charge accordingly.
(I even have about twenty customers in a long road of about 50 1930's semi's where most have extended or put garages on and so made access to the back difficult) I just price for the fronts at a tenner a pop and do the backs on request if they are in and can let me through the garage or open the side gate.)
TL/DR: Set out your stall and some tips as to how I do that.