Since this is on an EMM day, I would guess that you would be held in some way until general park opening. I know for sure that you cant "wander" the park. Even before EMM when we had a prepark opening ADR if we finished before official park opening we could only go so far before we were held by castmembers. Example: we finished bfast at crystal palace and continued up through the castle toward fantasyland but were held by rope and castmembers just outside of the castle exit. When the park officially opened, we were allowed to proceed to the rides.
With this being an EMM day, even if you finish your bfast early, I dont think you will be allowed to enter the ride lines until official park opening since that priviledge has been granted to those who paid for it with EMM. Just a guess though....