From Episode 8 to Episode 19 it's only been 4 months? Where 2 months of the that the brothers were locked up....... so does that not make sense to anyone else or is it just me? In a few episodes "they" would say "it's been a couple weeks"
And there were weeks/months between when Mary joined the BMoL and when she told her sons about it. Plus, there were at least a couple of weeks that the Winchesters were working for the BMoL before Sam told Dean about it. Time is always screwed up on this show. If you think about the year that Sam's soul was in the cage or the year that Dean was in Purgatory, those didn't really effect the overall timeline of the show either. It's still up to date with where we are now. The way I usually see it is that the episodes we see are sort of like the most important snapshots of their life. Sometimes those snapshots happen back to back, but if that happens, then maybe the episode after that will cover a snapshot months later, because it's a case or a part of the myth arc that impacts on their lives more than the stuff we don't see. Or maybe if there's a time jump of a year between seasons, it means that the episodes we saw all happened within a relatively short amount of time, the gap year happened, and then the episodes we see when they come back the next season all take place over a relatively short amount of time, so everything still lines up with the current date. It's a lot of mental gymnastics to make it work, but the alternative is to not notice and not think about it, which I'm okay with doing too.
I know what you mean....and for some reason I cannot ignore the things that don't make sense, but S12 has a lot of that, so if I must not think about it, I guess I can.