This is a great question. We have been testing at various stages of bloom and we have noticed with most (not all) strains that the cbd peaks just before the trichomes turn amber and start to degrade. We did notice the highest points were typically 2-3 days before the glandular trichomes started to amber up was the peak window for the highest CBD content.
We still need to do much more testing to verify this and we will also need the community's help with there own independent testing at varying stages of bloom
All the best
Mark.