This is Carlton here. Just now I received a call from the Kumamoto Vaccine Center and was thanked for my using the website to make a reservation.
Then the reservation time and place for my first inoculation was confirmed, and I was offered a reservation for my 2nd jab, exactly 3 weeks later, which I snapped up at the same location and in the morning.
So it looks like Kumamoto is getting the kinks worked out of its system.
I was hoping to get an official confirmation by either call or email and I did. Good luck everyone else who makes a try for themselves or elder friend or relative on Monday morning.
And stay safe everyone.