Jetstar has theirs right now, so June 9th or 10th every year. Kogan has theirs during September.
Which other companies do the same thing?
It's very easy to remember Black Friday/Boxing Day/Back to School sales etc, but it would also be good to know if it's worth waiting for a birthday sale too.
You mean the store's own birthday? PnS stores do that on their birthdays (each stores have their own birthday sales), BUT, searching back their individual FB pages, I'm beginning to suspect they don't really have a fixed birthday (even for the same store), just random "birthday" specials at different times of the year…haha
Some companies "celebrate" your birthday: your health insurance and life insurance premiums go up on your birthday!