Hi
I need to call BA to add the return flights on a 2for1 avios/companion flight. I understand I need call on midnight as the flights are released then.
Research suggests that Japan is the best to call atm as USA is closed. I see Japan is +8hrs ahead GMT. Does this mean I need to call them at 0100hrs as it wont be 9am in Tokyo until then, as we are currently UK BST not GMT. Or am I wrong?
Grateful for any assistance.

Many thanks