>>18094638
I would select an appropriately discreet and open-minded king of medieval England or France (my ancestors) to contact with a most intriguing proposal. I would recount the founding of America in our timeline and the naval advancement of iberians that made it possible. That would get their attention. Then I give enough advancements to start an industrial revolution immediately: steel founding and firearm technology, electricity, modern biology. With my patron thus occupied, I set off in strict secrecy on a well-equipped and armed mission to the new world.
Once on American shores, I give diseases to the locals and subjugate them, but not as bad as the real colonists did. Generally speaking I use them and my select crew to create a master race that will rule the earth for 10,000 years. Europeans will try to invade America towards the end of my natural life, but I will have applied modern politics and economy to confront them with an enormous unified nation. Soon after my death, America will have technological parity.