Hi
Sounds like a plan. The Lynx bus is every half hour and its around a 20 minute non-stop trip that drops you at the TTC next to the monorail station where Epcot beckons. Just a question of allowing some time in case of delays so you can arrive ahead of your ADR time.
We're doing a similar thing. We have booked a one-way transfer to Seaworld in the morning. We have used the bus before but its a three stage trip (resort bus to MK, monorail to TTC then catch the bus) and wanted to be there on the dot. However we'll be using the bus on the way back as we have dining reservations in the MK (LLT).
Cheers