The easiest way to get from the Poly to EPCOT is to walk over to the TTC. Do NOT take the resort monorail to the TTC as that could take 25-30 minutes or more, depending on how crazy things are at the MK stop. It's about a 5-minute walk to the TTC from the Poly and they are literally next door to each other. There is a marked pathway to the TTC. Just follow that. The TTC is to the right of the Poly as you look at them from the front.
At the TTC you will want to get on the EPCOT express monorail.
It's a much shorter trip this way than taking the resort loop monorail all the way around, then transferring.