It is not clear to me when advance upgrade space is released: in past years it has sometimes been released in batches a few months ahead, but maybe now just 329 days in advance?
A few weeks before departure it is easier to assess your chances from the seat map. I normally book a few months before travel so have typically been first on the upgrade list, and have almost always been upgraded even on apparently full flights. (But no longer when EQD priority is introduced.
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