It has come to my notice, that according to general Mundus history, the first successful state is established in the early 1700s, suggesting that socialism exists in the 17th century.
Assuming that the industrial revolution took place at the same time period as it did irl, socialism, an ideology that emerged as a result of factory-wage labour, appears before the causes that caused it to emerge irl.
If we want to make other comparisons, the first successful liberal state (a decidedly less radical ideology) only emerged in the mid 1700s.
Put simply, the timescale for socialism as an ideology makes very little sense and has complicated implications.
My suggestion is thus that the birth of socialism is pushed back to the 1820s, with the first socialist state emerging no time before the 1840s.
These numbers are below what I'd like, but I wish to avoid complicating any historical revisions that will undoubtedly need to take place.