I eliminated Sitting Bull in 150 AD. I attacked Monty next, bribing Roosevelt to join me in the war. (Those two were worst enemies with each other, so I was surprised they hadn't started fighting sooner.) Monty's eight cities were all mine by 1120. By this point, my caravels had also found the other continent. The circumnavigation bonus would come in 1230.
Also in 1230, I attacked Justinian. Once again, I bribed Roosevelt to be my ally. I also adopted Roosevelt's Judaism, hoping to get him to peace vassal to me. That hadn't happened yet, when Justinian capitulated in 1290, after having lost four cities to me.
I didn't want to launch an naval invasion while Roosevelt remained independent, so I declared war on him in 1340. I captured New York and Washington (with five wonders, including the AP) and he bent the knee in 1440.
Tokugawa was my next target. I started this war in 1515, which turned out to be too soon, since I still didn't have enough galleons to ferry across my entire army (which at this point included cuiraissiers). I captured and held Tokyo, but I wasn't able to hold Nagoya. More research brought cannons, rifles and cavalry online, before Tokugawa capitulated in 1555.
I'd follow up with an attack on Charlemagne in 1560. I took Florence, then discovered Charlemagne had his army stationed nearby. He foolishly moved that army into the open to attack one of Tokugawa's border cities. My forces (many of them freshly upgraded) wiped out that army, and Charlemagne immediately threw in the towel. I liberated a couple cities, to ensure that I was under the domination land limit, and a conquest victory was mine in 1575.