At one time there used to be posts that tried to estimate it, sometimes in the old Mini RTW thread. I don't know if any are left or anyone else knows the timing of when reward seats are released. Other than that, it's trial and error. Just looking at the site and doing searches over a number of days to see when the flights are added. I was watching Ethiad because I thought that was the best bang for my points from YYZ and there wasn't much other availability to Australia outside of AC. I think the reward seats generally came out about 10 months in advance. Can't recall for certain though. Going from Vancouver maybe Asiana or ANA are your best shot. Not sure if they're still showing up on searches due to AC IT and covid travel restrictions. Maybe someone else has a better idea..When the AC reward seats do come out they generally are less points than if you wait, but I still found them to be more than non AC partners.