XY: Revealed in January for October. February had Sylveon, March weirdly had nothing, April had The Mysterious Pokemon Who Has a Relation To Mewtwo. May, June, July, August, September all had consistent stream of normal information.
ORAS: Revealed in May out of the blue, presumably for financial reasons. June, July, August, September, October all had information.
SM: Revealed in February. March & April were silence this is where we had the infamous double spread of "the boxarts, but the cover legends rae blurred out". The true dark ages, for sure... Anyway May, June, July, August, September, October all had information.
USUM: Revealed in..wow June? Really? Bizarrely late for this thing. July had minimal (steel book, mostly), but August, September & October had consistent information.
Let's Go: Revealed in May for November release. June, July, August, September, & October all had new (or..."new", as the case may be) information revealed about the titles.
SWSH: Revealed in February for "Late 2019". March, April & May were very slim, beyond CoroCoro revealing the contest for Steel Beam in April and a Uniqlo design & Home compatability in May. June, July, August, September, & October all had new information, even if SWSH's news drops were lesser per drop.
And all of these also had information in November (or, October rather, for XY) just before they released.
So my apologies about "6+" months, but the average is we usually get 5-6 months of steady information (6-7 if you want to count the release month since there is usually stuff before the release). and between reveal & the news cycle picking up it's typically only a 1-3 month wait
Thus, BDSP is really the outlier here. Legends Arceus at least has the excuse of not releasing until January, but....