Presuming you are talking about European or domestic flights: if there is award availability in Club Europe, then in my experience it is highly likely that economy seats will open at about 1am ish the day prior to travel. If they are not available, then in some (but much fewer) cases economy seats can open up on the day of travel too. At least - as a gold cardholder - this has been my experience the past 18 months or so as I've been burning down my points balance. In my experience, availability dries up about seven days beforehand. Then if there are Club Europe seats available, economy seats will tend to open up in the 48 hours prior to travel - typically at about 1am ish the day before.