We are assaulting the MK on June 29th with a group of 14 and I was able to secure an 8:10 BOG breakfast for the entire group. I have read several reviews of people enjoying the BOG breakfast and being able to quickly jump into the 7DMT before the masses arrive and exiting just as the line begins to form.
I have heard that the cast member holding back the breakfast reservation guests from entering the attractions:
waits until the hoards from RD are within eyesight, before releasing the BOG guests.
release the BOG guests at the end of the welcome ceremony.
at about 8:47 the cast memeber walks the BOG guests to the 7DMT FP+ entrance
I did this on Memorial Day morning with great success! @999HappyHaunts and I had to hustle a bit, but we made it to 7DMT literally seconds before the hoard of masses arrived. The coaster was already running. It was about 8:40ish when we got to 7DMT.
We just enjoyed BOG breakfast June 7th. We were able to ride 7D 3x prior to rope drop crowd that morning! We never were held at BOG. We came out of restaurant around 8:40. Hope this helps-have a great trip!