I am wondering this too. From my research they don't officially start meeting until 9, even on early morning hour days. We are planning to attend Epcot EMH in a few weeks and definitely want to meet them. I am now wondering if the line builds during EMH, basically if we would spend the entire hour of the EMH waiting in line? If that's the case I might just try for RD on a non-EMH day, but we only have 3 park days planned this trip and our other 2 were going to be spent at MK. Really hoping we can get to meet them early during the EMH morning at Epcot.