If you just want to ride the monorail and are going to spend time in Epcot, I recommend taking it from there. To do it from the MK involves the TTC setup. At Epcot you get on it just outside the gate and can ride it in the loop to TTC, without having to get off, back to Epcot. If you use the TTC parking lot you can just get on it at TTC, ride it to MK stay on and go back around or get off at MK spend whatever time you planned there and get back on it to go back to TTC and the parking lot.
You can also go the Epcot way and get off at the TTC, get on the MK line, ride around back to TTC and then switch over to the Epcot line and head back there. No one train does the whole thing (MK and Epcot) you have to switch, so if you just want an easy ride get on at Epcot and ride to TTC and back or Get on at TTC and ride to Epcot and back. Lot's of options depending on your schedule.