There seems no special significance to the year except that it is the threshold between the centuries, and just barely in the 19th, the century of massive technological and demographic change. The date is under two generations before the railroad, which, with the Industrial Revolution, accelerates large demographic changes. By about 1850, more people in England will live in towns and cities than in the country. On the cusp of two worlds, the novel's people and locale are exotic to a mid-Victorian audience that is becoming highly urbanized and industrialized yet not unbelievable. Lockwood's background and disposition allow him to speak to the novel's contemporary readers as something like one of them. He is their and our guide, if an undependable one, into the novel's world.
Brontë and her father often visited a nearby manor house of grand proportions, Ponden House. On Ponden House's lintel (the weight-bearing stone or beam over a doorway) was engraved "1801," the year being that in which the Tudor manor had been renovated. She may import Ponden House's affluent size and appearance into her conception of Thrushcross Grange, and at the same time the elaborate carvings over Ponden's front door seem also to inform her conception of Wuthering Heights. So Ponden House in its pre-renovated condition may have served as a model for Wuthering Heights and, renovated, for Thrushcross Grange.
Brontë's imagination is eclectic, sifting among experience and hearsay in order to reinforce the novel's realism.