Sense & Sensibility and Pride and Prejudice were both written before 1811, though not published until then! tbh they're both set in the 1790s, which is something that often bugs me about all the adaptations that have the costumes from the publishing date, not the actual setting in the novels.
I remember reading this someplace. There may be something in the books that makes it possible to date them to the 1790s, but I don't know what that would be.
it's the stuff about the regiment/military, mainly! I don't know about her other books, but those two were written in the 1790s, too, then revised for publication. One of the things I noticed in my Early Eng Novels courses was how novels were almost always set in the past, even if it's recent past
There are really no other references to what's going on in the world, other than probably in Mansfield Park (whose title always cracks me up—it's the name of a park in my hometown).
That would have been my guess!
It always amuses me that Jane Eyre would be more likely to wear the high-waisted Joséphine dresses than the mid-century crinoline/hoopskirt ones she's so often portrayed with, just as the Dashwood and Bennett sisters would be more likely to wear hoops and chemise dresses.