I think the answer to that would be made up of these parts: 1.how educated that man is in science, since that the raw scientific knowledge he can implant in that time period 2.how skilled is that man in persuasion, diplomacy and cunning. since that would allow him to rise to a position of power and not get overthrown over his radical ideas. We must remember how superstitious people were at that time. 3.how rich are his surroundings, for him to be successful in changing the world, he has to be able to provide for the people working for him AND to have enough funds to fund his ideas and "inventions"
Assuming he has all three and also luck on his side we could assume he would be able to rise to a position of power (either by economical gains or militeriatic excellence, easiest way is probably to commission air balloons and demolish enemy moral and forces) and gain lands and serfs, or workers... now he has a workforce and he could begin the technological improvement
First he would tackle the metal industry - steel was already invented so all is left to do is shape it, into coal engines and rails, now he has trains to move stuff and further his economical power. Also mining and electricity production, really just open the first factories. Second agriculture - reusing feces on fields is easy, and the metal industry would ease manpower on the fields. He could also begin selective breeding in plants as well as in animals. 222
Health - on any territory under his control a sewer system would be built, soap is easy to make and would be the first step in stopping desease, extending lives. Military - even if this man would make enemies - once he rises to power he would be able to defend himself, as even a small army could bomb a alrger one from above, or with mines from below. With steam engines even primitive tanks are possible, so even conquest would be a breeze. Trade - with a train that could be made to reach pretty far the man could establish merchent guilds, as profit seekers would sieze an opportunity. Other kingdom around would grow dependant on him, and thus his power would grow.
Now our guy has a prospering little haven of a kingdom. It's time to take on social policies and further expend the economy First would be establishing an academy and the rules for scientific method. gathering the best minds around with lucrative work offers, next recruiting and training teachers to spread knowledge and his values into young minds so his legacy would keep on going after him
I think that at that point the trade would spread further and bring to other places the ideas that this little kingdom has to offer. thus scholars would flog to it out of curiosity, capitaling on ideas of innovation. Grand change is almost imminant, not even A plague can erase that level of change in thought pattern (I'm talking about imperialistic view).
At least that's my bit 222