You could take the bus to Epcot, then the monorail to the TTC, then the monorail to MK. Or go from the MK bus stop straight to the monorail, ride the entire loop, and arrive [back] at MK.
You could take the bus to Epcot, then the monorail to the TTC, then the monorail to MK. Or go from the MK bus stop straight to the monorail, ride the entire loop, and arrive [back] at MK.
If you want to arrive at MK by monorail, coming in via Epcot is a good plan.
But be aware that it likely will not get you to the MK by rope drop, and that for now thru this summer, the trains are starting up late 3 days a week.
Also, there is no direct platform-to-platform transfer at TTC from Epcot to MK. You will need to exit the station and re-enter, and probably wait in a queue if you're traveling in the morning.