For a 7am park opening, the busses will begin running about 6am - keyword is "about". Don't plan on them running as frequently for that first hour. Be at your bus stop at 6am, as the Swan is typically the first resort on that route which at that time of the morning is likely to include all 5 of the Epcot resorts. The second bus likely will not arrive until 6:30-6:35 and you won't make your 7am ADR if that's the case.
Steve