Thanks for the bump. I meant to give you my WAG, but I forgot.
WAG: I think concert ticket sales are the responsibility of the venue owner (arena, concert hall, theater, whatever). They then shave the money with the band, manager, promoter, etc. Whether this is a flat dollar sum or a percentage of sales, I don’t know. Since the venues are owned by different people who don’t act together, they go on sale at different times.