If you place the Plague just before or just after the Medieval Warm Period's end, You'll wind up with more people dead from starvation and fungal infections.
That's actually a good thing. It means the survivors have more wealth to invest, & will be able to demand higher wages. Because of greater labor demand, there will also be greater need for technical innovation in tools. There will also be more agricultural surpluses, meaning more wealth for farmers & less famine. This presumes new ag tools don't happen, & they will; the greater overall wealth means there will be more animals (mainly oxen) available, too: both these things mean ag production is higher TTL than OTL, with even stronger wealth/famine knock-ons. Frex, better ships to move the ag produts. Or increased demand for luxury good thanx to more wealth, which increases demand to find a North West Passage & leads to earlier trips to North America. (This obviously means adding the wealth & ag production from there.) Who does this is likely to be much different than OTL.
That said, I don't see how you move the Plague back...


It's a natural process.
The only power with a chance for a "modern" world of the industrial sort (presumably also including its vices) would be Song China in the Medieval era. And if the Song are creating an industrial empire with the resources available to a Son of Heaven, it's debatable what anyone could really have done to *stop* them. At that point minus the Mongols gunpowder hasn't really spread west yet, and a China that goes to war with a 17th-Century style muskets, pikemen, and plate armor military against its neighbors and Europeans is a completely different scenario than OTL.
One problem: it will never happen in China. Ever. The culture is opposed to innovation & industrialization, the government controls all industry, & there's nothing like primogeniture, so the increase in private wealth that heavily drove the IR in Britain is impossible in China.