It is the far left tapstile. It is likely that a line will start forming around 7:30 or so. A CM will go down the line, verifying your breakfast reservation before they start letting people in (they'll redirect anyone without a breakfast reservation into another line). We've always done 8:00 breakfasts at H&V, and they've never let us in more than a few minutes prior to 8:00, so you probably won't be in super early. 8:00 is the first breakfast slot and there's really no reason to let people in earlier than that since there's nothing else to do other than walk straight to the restaurant (internal ropes keep guests from where they don't belong that early, and nothing else is open). I'm sure the Sci Fi breakfasts will be offered in a similar manner, though hopefully they'll have more than one tapstile open. Last time we were there (in October) there was a quite a line built up before they started letting people in for their breakfast reservations (but they also seemed to be having an issue with the MBs/tapstiles in general that day, so the long, slow line may have been a fluke).