Subscriptions and reminders are processed over night beginning at about 3 AM Eastern which is midnight Pacific time.
They do not run by time of day.
So there is not a native solution but there may be others who might chime into this thread with a non-native solution.
It is possible to trigger a subscription and hence presumably a reminder (but I have not tested that), with an API so if you can have some external service call the API on a timer then you could get it to fire in the middle of the day in a particular time.
