This is controlled from the Cut Off Timer admin page, not the main Client Config tabs. For each weekday, you set "How many days to close?" and "Time to close" — for example, setting Friday to "1" day and "5:00 PM" closes Saturday's delivery date at 5pm on Friday. The page has separate Meal Prep and Retail tabs, so the cutoff can differ between standard meal-prep ordering and retail/POS-style ordering. Once a date is past its cut-off it's marked closed and dropped from the date picker; if an admin manually reopens a date after it was auto-closed, that reopen is honored and the date won't be silently re-closed by the same math.