My experience, as others here, it's a bit hit and miss. Either it clears within a few days or not at all. I waitlisted a one-way to MXP in May, I think, for travel last August and it cleared in a few days. However the dozen flights back in September did not clear, so my back-up plan was to travel in Y (only available confirmed flight 
). Have already booked 2023 flights.
