Does anyone know what hours the China Airlines San Francisco counter is staffed? Also how far in advance of a flight can the airport counter (or other channels) assign blocked seats?

We have an economy res with no seat assignment available currently. There are a handful of scattered empty seats and quite a few blocked seats but none available for assignment currently with the booked ticket class according to phone reservation agents. We are looking for a block of 3 seats together. At what point does CI release blocked seats for assignment and through what channels (airport only, phone reservations, online)? I am thinking about going to the airport a day before the flight to get seat assignments if the airport is the only place it can be done. Thanks for any insight into the process.

On other flight segments one phone agent was able to open up some not blocked but unavailable for online assignment seats for me but those flights had many more open seats. The first outbound SFO-TPE has a pretty full seat map and the agent said they could only open seats towards the back of the plane for our ticket class but all the seats in the back were taken so he was unable to do it. Another agent later said that they were not allowed to open any seats and that if someone had done that for me it was against policy -- oops.

ETA: Also, at T-24 are the blocked seats available for assignment at the airport kiosk machines or only at the check-in counter (in case the counter is closed)?