Gee whiz, it's a good thing you guys don't teach this stuff..
It's 1 mile inside or outside of the arc..there is no speed requirement other then airspace rules...so if under 10k, then 250kts would apply.
ATP standards, or professional standards may apply that once established, pro level would be to hold inside of a half mile in or out of the arc or better, depends on who's holding your feet to the fire.