Monarchs cares about power. Give the ruler some more metallurgy or siege engines first, so you have their favour. Then split the Royal Court's physicians into two groups, one that washes their hands, and one that doesn't. Do the same for leeches, bloodletting, hydration, etc. It'll be hard to argue with the resulting death rates. And in the long run, you'll have a much bigger impact by introducing empricism/A-B testing/evidence-based medicine than any one thing specific thing you could have done.

But on the other hand, there's a decent chance of you worked hard enough, they could probably get there at least a century or two after your death.

Yes, most of my plans for myself run on the unspoken assumption that I am not dead.

Or drown because the Pythagoreans hate your guts

Non-historian detected

They had citrus fruits. It wasn't a mind bending concept.

Ok fine but the smallpox would have killed me before that happens