Time to close is the clock time on that weekday at which the rule fires. The scheduled job runs several times a day; on the configured weekday it does nothing until the current time is at or past this value, then closes the dates in the window. On the storefront the same time is used to decide whether a date's cut-off has already passed. The time picker only offers hours 01:00 to 22:59.

If the time is blank (or the weekday is switched off, which stores 00:00), the job treats the trigger as midnight, i.e. it fires on its first run of that day; the storefront treats a blank time as the end of the day (23:59) for the same rule. To avoid that mismatch, always set an explicit time on every enabled weekday.