Yeah, you won’t be able to walk through Epcot that early. Epcot opens at 9am (nearly) every day of the year with an 8am EMH (roughly) once per week, so no options to cut through that early.
Options... take the bus to MK then:
1) Resort Monorail around to Poly. It will stop at CR, TTC, then Poly. The Resort Monorail usually starts at 7am under normal situations, but check the Times Guide each week when there just to be sure.
2) MK/Poly/GF boat. It will stop at GF first then on to Poly. Although this is on the early side for the resort boat, so I’d only do it if I happened to see a boat arriving or loading right when walking by (you have to walk by the boat dock on the walk to the Resort Monorail).
Minnie Van/Uber/Lyft/Taxi would be more efficient alternatives if you don’t want to mess with the transferring involved with the above options.