Common misconception...
As trichromes amber and THC degrades it converts to CBN not CBD. It does have some similar effects as CBD though.
According to this article from 'clear'
http://www.clear-uk.org/the-importance-of-matured-cannabis/
"CBD is produced later in the bud production cycle"
And:-
"But until the plant reaches the final weeks of flowering, the main content are the THCs, terpines which are responsible for the increasingly powerful smells of whatever strain/hybrid they are, and have practically no CBD content and the terpines are still mainly smell and haven’t converted to terpenoids"
"THC D9 is a potent stimulant and if plants are cropped too early, any cannabis will have little or no CBD and will only provide a very stimulant high".
"The anecdotal evidences for the reactions people have to immature cannabis is all over cannabis community forums, of every country around the globe, especially on the cultivation forums, and that is where legislators need to go and look properly at what many academics involved with cultivation, many very experienced people who understand cannabis and the stages it goes through as a high order plant, so they can stop being guided by those who in comparison, have nothing but a basic and tenuous understanding of cannabis"
"it is during the final weeks that early THC production in the trichomes on the leaves and buds increasingly start to oxidise and CBD and other high/stone stabilising oxidase are created".
Makes me wonder if anyone has any real proof about CDB in Cannabis, or is it just all sales hype.