I tally which weekdays are used within the month, and charge a minimum of 3 days a week at a higher daily rate. If they use each of the weekdays at least once a month(ie mon/tues/wed/Thurs/fri) then full time fees are charged, as I can’t fill the spot on weeks not used. Once they hit at least 4 weekdays, then it’s full time care, again I cannot fill in the gaps on a rotating basis.
Someone who is already asking about late pickup in the interview is a big red flag to me! I don’t let clients attend for my full operating hours, I have all of them on fixed contracted hours, and if they go outside of those hours, late fees are charged.