In July 1848.
Serial publication of William Makepeace Thackeray's novel Vanity Fair by Punch magazine concludes. It appears in book format by Bradbury and Evans in London, with illustrations by the author.
It was printed in 20 monthly parts between January 1847 and July 1848. The first three had already been completed before publication, while the others were written after it had begun to sell.
https://en.wikipedia.org/wiki/Vanity_Fair_(novel)
Vanity Fair at PG:
https://gutenberg.org/ebooks/599