You need to optimise food selection with respect to how long it takes them to get it and how long it takes you to eat it.
Have someone order the same thing you wanna get just three minutes earlier and have him run off without paying or taking it. That way you can be sure your menu's ready. But this sure does count as luck manipulation.
rofl... if I can get ahold of a video camera, I might show you a TAS McDonald's route. You can get to the place in about 30 seconds using a well-executed BLJ. I'm still working on luck manipulation at the counter; the RNG for a quick employee is tough to crack.