How do you get from the Poly to Epcot before park opens for 8am ADR? I don’t think the monorail is running yet…??
There should be a bus at POLY for dining. Check with concierge to check for the times and to let them know you need one.
Or you can UBER/cab it.
There is transportation available. With all the Resorts offering even earlier Breakfast options. You should have no issues with the Monorail or a bus.